On July 21, in what could be the last picture of the comedy giant, Robin Williams posted this photograph to Instagram on his birthday of himself and his Night at the Museum co-star, Crystal the monkey, who will also be familiar to viewers of the Hangover trilogy

Dearest wish: A shot of the marquee at the Laugh Factory in West Hollywood paying tribute to the late Robin Williams on August 11, 2014 in Los Angeles, California

Poignant: Flowers, messages and other tributes are scattered across the comedian's star on the Holywood Walk of Fame as fans come to terms with his death

Family: Actor Robin Williams and with then wife Marsha Garces Williams, sons Cody, Zachary with girlfriend Alex, daughter Zelda arrive at the 62nd Annual Golden Globe Awards in 2005

Poignant tweet: Zelda Williams posted an Antoine De Saint-Exupery quote from The Little Prince on Monday following her father Robin Williams's death

Tragic loss: Zelda tweeted on Monday following the loss of her famous father, pictured together in 2011

Devastating: Robin Williams with his third wife, Susan Schneider, who he married in 2011. She released a statement on Monday after his tragic death

Patrol: A Marin County sheriff drives by the home of actor and comedian Robin Williams on August 11, 2014 in Tiburon, California after the Academy Award-winning actor and comedian was found dead in his home on Monday

Last seen: The comedian was last seen in public in June at San Francisco Zoo where he fed a howler monkey that was named 'Robin' after him

Known as 'the funniest man alive', Williams fought drug and alcohol problems when he became the star of Mork & Mindy, on his path to stardom.

He had stayed mainly sober for 20 years but in July he went into rehab to use the 12-step program he championed, this time during a brief stay at a Minnesota facility.

One of his last photographs: This photograph of Robin Williams was taken in July at a local Dairy Queen in Minnesota during his stay at a rehabilitation facility which he checked himself into for treatment for alcohol addiction

Publicist Mara Buxbaum said at the time that Williams had not fallen off the wagon, but was 'taking the opportunity to fine-tune and focus on his continued commitment, of which he remains extremely proud.'

This year he has six movies either out or due for release and has also been working on the TV series The Crazy Ones.

Off stage and camera Williams had endured a struggle with personal demons that manifested themselves in well publicized drug and alcohol problems.

Williams was a close friend of Blues Brothers and Saturday Night Live star John Belushi and was one of the last people to see the actor alive before his death by drugs overdose at the Chateau Marmont Hotel in Los Angeles in 1982.

The star of Good Morning Vietnam said that experience forced him to evaluate his own wild lifestyle and led to him seeking help for his addictions to alcohol and cocaine.

'Was it a wake-up call? Oh yeah, on a huge level,' he once said.

Williams managed to maintain his sobriety for two decades but in 2006, relapsed and sought treatment.

Williams described his family's reaction to this relapse in a September 2013 Parade Magazine interview: 'It was not an intervention so much as an ultimatum. Everyone kind of said, 'You’ve got to do this.' And I went, 'Yeah, you’re right.'

Iconic: Tributes have appeared at the Boston bench where Robin Williams' character in Good Will Hunting gives a monologue on life, love and art to Matt Damon's Will

'I'M SORRY TO BE BREAKING THIS NEWS': CONAN O'BRIEN FORCED TO REVEAL ROBIN WILLIAMS' DEATH DURING FILMING OF HIS TALK SHOW

In shock: Conan O'Brien was forced to reveal to his audience that his friend Robin Williams had died

TV talk show host Conan O'Brien emotionally broke the news of the death of his friend Robin Williams to his studio audience during filming last night.

His voice cracking with emotion, O'Brien, who interviewed the Hollywood star a number of times, announced the news to gasps of astonishment from those watching.

Sombrely facing the camera towards the end of filming, the 51-year-old said:'This is unusual and upsetting, but I've got some news during the show  that Robin Williams has passed away.

'I'm sorry to everyone in our studio audience that I'm breaking this news. This is absolutely shocking and horrifying and so upsetting on every level.

'We're absolutely stunned to get this news,'

His guest, Canadian comedy actor Will Arnett, who appeared in the 2006 road comedy RV with Williams, added: 'As funny as he was - he's one of the all-time greats - he was even better as a person.

'He was just the loveliest and one of the kindest guys that anyone ever worked with.'

Watch Video Here:

Oscar winner Robin Williams dead at 63

A look back at Robin Williams in Mork and Mindy

His divorce from his wife of 19 years and mother of two of his three children, film producer Marsha Garces, came a couple of years later and many outside his family's inner circle opening suspected his substance abuse struggles were to blame.

The relapses, it seems, had happened before. In that same Parade interview, Williams described a 2003 relapse, which came after 20 years of sobriety, to the magazine: 'One day I walked into a store and saw a little bottle of Jack Daniel’s. And then that voice—I call it the lower power—goes, "Hey. Just a taste." Just one.’ I drank it, and there was that brief moment of "Oh, I’m okay!" But it escalated so quickly. Within a week I was buying so many bottles I sounded like a wind chime walking down the street. I knew it was really bad one Thanksgiving when I was so drunk they had to take me upstairs.'

He described feelings of loneliness and fear that pushed him back towards alcohol at the time he was filming Christopher Nolan's Insomnia in Alaska with Al Pacino.

Inside: These real estate pictures show the interior of the home in Tiburon, California which is owned by Robin Williams and his family and where the comedy legend was found dead on Monday (pictures date from before Williams purchased the home)

Luxury: The pool inside the San Francisco area home owned by Robin Williams taken by realtors before the legendary comic purchased the home

Touching: AJ Polis leaves a flower alongside a placard and a photo of the late actor Robin Williams as Mork from Ork, as people pay their respects at the home where the 80's TV series "Mork & Mindy",was set, in Boulder, Colorado

Sure to grow: A bouquet of flowers and a mock Oscar statue lay on Robin Williams star on the Hollywood Walk of Fame in Los Angeles on Monday

Commemoration: Flowers are placed in memory of actor/comedian Robin Williams' Walk of Fame star in the Hollywood district of Los Angeles on Monday

You will be missed: Flowers are placed in memory of Robin Williams, the Academy Award winner and comic supernova whose explosions of pop culture riffs and impressions dazzled audiences for decades and made him a gleamy-eyed laureate for the Information Age

Public thanks: Flowers are placed in memory of actor/comedian Robin Williams on his Walk of Fame star in the Hollywood district of Los Angeles

'I was in a small town where it's not the edge of the world, but you can see it from there, and then I thought: drinking. I just thought, hey, maybe drinking will help. Because I felt alone and afraid. It was that thing of working so much, and going f***, maybe that will help. And it was the worst thing in the world.'

In a revealing interview with ABC News' Diane Sawyer in 2006, the legendary comic opened up about drinking again and said that his descent back into alcoholism was 'very gradual'.

'It's the same voice thought that … you're standing at a precipice and you look down, there's a voice and it's a little quiet voice that goes, 'Jump,' Williams told Sawyer. 

With trademark humor, Williams attempted to make some light of his battle with the bottle during his interview with Sawyer, calling addiction a predator that lies in wait and is always present.

'It's fine now, I'm OK. Then, the next thing you know, it's not OK. Then you realize, 'Where am I? I didn't realize I was in Cleveland', he said.

While he recently sought help in Minnesota, in 2006, Williams spent two months in Oregon's Hazelden Springbrook treatment center.

In 2006, he said that he was only drinking, having kicked his well-documented problems with cocaine.

Williams often seemed at odds with his public persona, struggling to be seen as something more than just a man with a gift to make people laugh.

'It's hard because people want to know you're a certain thing,' he told The LA Times in 1991.

Watch Video Here:

Archive: Robin Williams walks red carpet with wife and daughter

Archive: A montage of Robin Williams' best movies

'They still say, 'That's the little manic guy. He's the little adrenaline guy. Oh, yeah, he touches himself. He doesn't do that anymore. But wait a minute. He's the little manic guy who played the really quiet guy and then the really scary guy. Oh, no, wait....'

Others often saw his manic need to tell jokes as a classic shield to hide his real feelings.

'He was always in character — you never saw the real Robin,' said Jamie Masada, founder and chief executive of the Laugh Factory to The LA Times.

'I knew him 35 years, and I never knew him.'

'He was a wonderful guy,' Masada said to The LA Times.

'I remember John Belushi and Robin, both of them always complained to me — no matter where they were people would recognize them.

'They sold their privacy to the public. They could be in the middle of talking in the street and someone would come up for an autograph.... he didn't realize how much he sold his privacy to people.'

Robin Williams’ half-brother has paid tribute to the star, saying he meant a �very great deal’ to him.

McLaurin Smith-Williams, 67, shared a mother, Laura McLaurin, with the tragic comic - who was found dead from apparent suicide at his home in Tiburon, California, earlier today - and is still coming to terms with the shocking news.

Father and daughter: Actress Zelda Williams and father actor Robin Williams attend the House Of D film premiere at Loews Lincoln Square in New York in 2005 and (right) Zelda seen in November, 2013

'VERY SAD, VERY UPSET': COMEDY LEGEND's ONSCREEN MRS. DOUBTFIRE DAUGHTER MARA WILSON LEADS TRIBUTES

Tributes were pouring in after the shocking news of Robin Williams' death broke on Monday.

Two decades on: Mara Wilson was six-years-old when she starred with Robin Williams in Mrs. Doubtfire and took to Twitter on Monday to express her grief at Robin Williams' death

Mara Wilson, who played his on-screen daughter in Mrs Doubtfire, was amongst the first to pay their respects to the late actor, whose tragic death aged 63 at his Tiburon, California home is being treated as suspected suicide.

The actress, who is now 27, was devastated. She tweeted: 'Very sad, very upset, very glad I did not have to hear about this though Twitter. Probably going to be taking some time off it for a while.'

Sally Field, who also starred in the movie, said in a statement: 'I feel stunned and so sad about Robin. I'm sad for the world of comedy. And so very sad for his family. And I'm sad for Robin.

'He always lit up when he was able to make people laugh, and he made them laugh his whole life long.... tirelessly. He was one of a kind. There will not be another. Please God, let him now rest in peace

Robin's representative told MailOnline: 'Robin Williams passed away this morning. He has been battling severe depression of late.

'This is a tragic and sudden loss. The family respectfully asks for their privacy as they grieve during this very difficult time.'

Sadness: The Matilda actress, 27, said she'd need some time away from the social network

Close: Mara played Robin's on-screen daughter in 1993's Mrs. Doubtfire. They are pictured centre with Lisa Jakub (L) and Matthew Lawrence (R)

When contacted at his home in Memphis, Tennessee, he exclusively told MailOnline: �I would very much not like to talk about this right now. He means a very great deal to me. Thank you.’

McLaurin has previously talked about how Robin and his other half brother Todd – who had the same father as the funnyman, but who passed away in 2007 – used to meet up with their families every year.

He told the Chicago Tribune in 1991: �All three of us grew up as only children - Todd, myself and Robin. I was adopted by my mother’s parents after her divorce from her first marriage. Todd grew up with his mother.

�We all get along famously. Todd is no blood relation to me, but we’re real close.’

Robin’s first two wives, Valerie Velardi, whom he was wed to from 1978 to 1988 and Marsha Garces Williams, whom he was married to from 1989 to 2008, have yet to comment on his death.

First wife: Robin Williams with his first wife Valerie Velardi, who was married to the comic from 1978 to 1988 and (right) his second wife, Marsha Garces, who was married to the Oscar winner from 1989 to 2010

The death of Williams has shaken Hollywood, and colleagues mourned the loss of what many called a big-hearted man and one of the most inventive comedians of his time.

'Robin was a lightning storm of comic genius and our laughter was the thunder that sustained him,' said Steven Spielberg, who directed Williams as Peter Pan in the 1991 film, Hook.

More tributes poured in after the shocking news of Robin Williams' death broke on Monday.

Ellen DeGeneres and Steve Martin were amongst the first to pay their respects to the late actor, whose tragic death aged 63 at his Tiburon, California home is being treated as suspected suicide.

'I can’t believe the news about Robin Williams. He gave so much to so many people. I’m heartbroken,' Ellen tweeted after hearing the news.

Wonderful tribute: The Academy of Motion Picture Arts and Sciences posted this touching message to social media to mark the passing of Robin Williams on Monday

'His heart was so big': Ben praised him as an actor, a friend and an all-around kind and wonderful person

Saying it all: Danny DeVito, who has known Robin for decades, expressed his grief with just one word

'I will miss him beyond measure': Kevin Spacey posted a sweet message about his late friend on Facebook

'Our sweet friend': Rita Wilson shared a photo from the last time she and Tom Hanks saw Robin a few months ago

Lost friends: Steve Martin starred with Robin in Waiting For Godot and was devastated at his pal's passing

'He gave so much to so many people': Ellen DeGeneres was one of the first stars to pay her respects

The actor's friend and contemporary Steve Martin, who he starred alongside in the play Waiting For Godot, said: 'I could not be more stunned by the loss of Robin Williams, mensch, great talent, acting partner, genuine soul.'

His Night at the Museum co-star Ben Stiller was overcome with sadness at the passing of his hero.

Describing meeting the comedy legend at age 13, Stiller wrote on Twitter that Williams' 'impact on the world was so positive. He did so much good for people. He made me and so many people laugh so hard for a very long time.'

Another comedy legend, Danny DeVito, simply wrote that he was 'Heartbroken' on hearing the news of Robin Williams' apparent suicide.

Double Oscar winner Kevin Spacey wrote that 'Robin Williams made the world laugh and think. I will remember and honor that. A great man, artist and friend. I will miss him beyond measure.'

His co-star Pam Dawber, who starred with Williams in his breakout role on Mork and Mindy said, 'I am completely and totally devastated. What more can be said?'

The comedian would often film segments for the iconic children's show Sesame Street and the program tweeted their tribute to Williams.

'We mourn the loss of our friend Robin Williams, who always made us laugh and smile.'

Dressed in drag for one of his most famous roles as Mrs Doubtfire, Robin Williams brought joy to millions with his performance as the Scottish nanny in the 1993 Hollywood movie smash

Big break to top of his profession: Robin Williams and Mindy McConnell in Mork and Mindy which ran from 1978 to 1982 and launched the comedian to national prominence before his Oscar win for Good Will Hunting in 1997 (right)

Former Tonight Show host, Jay Leno reminisced when he 'saw him on stage the very first time he auditioned at The Improv in Los Angeles. And we have been friends ever since. It's a very sad day.'

'We have lost one of our most inspired and gifted comic minds, as well as one of this generation’s greatest actors,' said Chris Columbus, who directed Williams in Mrs. Doubtfire'.

Ex-CNN host Larry King told the network that he would always remember Williams as 'a genuine caring guy. Not just a funny man, but a guy who cared about people.'

Henry Winkler of Happy Days shared the very first scene which introduced America to the character of Mork for a 1974 episode of the iconic comedy show.

Winkler told CNN that during the Happy Days scene he realized instantly he 'was in the presence of greatness.'

'I just realized my only job is to keep a straight face,' said Winkler, who of course played The Fonz.

'And it was impossible. Because no matter what you said to him, no matter what line you gave to him, he took it in, processed it, and then it flew out of his mouth, never the same way twice.

'And it was incredibly funny every time.'

Comedian and actor Eric Idle of Monty Python expressed his sadness too.

'I am sick with grief,' Idle posted. 'I can’t believe my lovely friend is gone. My heart goes out to his wife and his beloved children. He brought us so much joy and laughter.'

ROBIN WILLIAMS: ICONIC ROLES OF AN INCOMPARABLE COMIC GENIUS

Robin Williams first entered America's hearts as Mork in Happy Days and then Mork & Mindy

The kinetic bundle of energy that was Robin Williams took on many forms during a long and versatile career. He may have been best known for his fast-talking, funnyman roles, but he mesmerized in serious ones as well - creepy ones, too - and was memorable well beyond the big screen: on television, on the comedy stage, even on Broadway. Here are 10 of Williams' most distinctive roles - and the list could be much longer:

GOOD WILL HUNTING (1997) - A rare but welcome serious role for Williams, who played the stubborn yet empathetic therapist who was somehow able to help math prodigy Will Hunting (Matt Damon) figure out how to handle his life. Won a supporting actor Oscar.

MRS. DOUBTFIRE (1991) - Who couldn't love a bumbling dad who dressed up as a portly nanny - with a latex mask, a wig and a Scottish accent - in order to spend time with his young kids? (A sequel was in the works.)

ALADDIN (1992) - Will it ever be possible to see a cartoon genie and not think of Williams? Remember him shooting out of that bottle: "Ten thousand years will give you SUCH a crick in the neck!"

GOOD MORNING, VIETNAM (1987) - Williams' fast-talking style was perfect for the role of a DJ on Armed Forces Radio during the Vietnam War. (First Oscar nomination.)

ONE HOUR PHOTO (2002) - Another serious role, and it was a creepy one: Williams played a photo counter worker at a huge suburban store who got a little too involved in the lives of his customers when he realized one of them was having an affair.

Good Morning, Vietnam earned Williams his first Oscar nod and proved he had the chops to be a serious biog screen actor

DEAD POETS SOCIETY (1989) - Played an unconventional poetry teacher who taught his Vermont boarding school students to stand on their desks, think on their own, and "seize the day." (Second Oscar nomination.)

THE FISHER KING (1991) - Williams played a half-mad homeless man, convinced that the Holy Grail was sitting in the Fifth Avenue abode of a billionaire. (Third Oscar nomination).

MORK & MINDY (1978-1982) - Mork from Ork. Nanu, nanu. What more need be said? This TV series, a spinoff of Happy Days, is how many of us first learned of Williams' sublime nuttiness.

MOSCOW ON THE HUDSON (1984) - Williams played a Russian - and quite credibly, too - in this film about a comically lovable circus saxophonist, Vladimir, who defects while touring New York (turning himself in at Bloomingdale's, naturally.)

BENGAL TIGER AT THE BAGHDAD ZOO (2011) - Appearing on Broadway, Williams gave an admirably thoughtful performance in the role of a tiger - actually, the ghost of a dead tiger - locked up at the Baghdad Zoo at the time of the U.S. invasion in 2003.

Wake up call? Williams was a good friend and fellow hard partier of the late John Belushi, whose death from a drug overdose Williams would later call a wake up call

Touching so many lives: Young and old stars alike all wrote their favourite things about the talented actor

Mia Farrow was in shock as she posted: 'No! Robin Williams you were so loved. Awful news.'

Sharon Osbourne also shared her sadness on Twitter, telling her followers: 'I’m so sad and devastated to hear of the passing of Robin Williams.  My thoughts are with his family.'

Her son Jack added: 'RIP @robinwilliams you will be missed. Thank you for making us all laugh for so long.'

On Monday in California, the sheriff said, â€?An investigation into the cause, manner, and circumstances of the death is currently underway by the Investigations and Coroner Divisions of the Sheriff’s Office. 

�Preliminary information developed during the investigation indicates Mr Williams was last seen alive at his residence, where he resides with his wife, at approximately 10pm on August 10, 2014.

�Mr Williams was located this morning shortly before the 911 call was placed to Marin County Communications.

'At this time, the Sheriff’s Office Coroner Division suspects the death to be a suicide due to asphyxia, but a comprehensive investigation must be completed before a final determination is made.

�A forensic examination is currently scheduled for August 12, 2014 with subsequent toxicology testing to be conducted.’

Rest in peace: Stars gushed about Robin's talent and lamented losing him too soon

His family also issued this statement on the tragic passing of the Oscar winner.

'Robin Williams passed away this morning. He has been battling severe depression of late,' Mara Buxbaum, press representative, said in a statement.

From his breakthrough in the late 1970s as the alien in the hit TV show 'Mork and Mindy,' through his standup act and such films as 'Good Morning, Vietnam,' the short, barrel-chested Williams ranted and shouted as if just sprung from solitary confinement.

Loud, fast, manic, he parodied everyone from John Wayne to Keith Richards, impersonating a Russian immigrant as easily as a pack of Nazi attack dogs.

He was a riot in drag in 'Mrs. Doubtfire,' or as a cartoon genie in 'Aladdin.' He won his Academy Award in a rare, but equally intense dramatic role, as a teacher in the 1997 film 'Good Will Hunting.'

He was no less on fire in interviews.

During a 1989 chat with The Associated Press, he could barely stay seated in his hotel room, or even mention the film he was supposed to promote, as he free-associated about comedy and the cosmos.

'There's an Ice Age coming,' he said. 'But the good news is there'll be daiquiris for everyone and the Ice Capades will be everywhere. The lobster will keep for at least 100 years, that's the good news. The Swanson dinners will last a whole millennium. The bad news is the house will basically be in Arkansas.'

Sadly though, his undeniable success did not always bring Williams the happiness his gifts gave audiences.

•  For confidential help, call the National Suicide Prevention Lifeline at 1-800-273-8255 or visit http://www.suicidepreventionlifeline.org/
•  For confidential support on suicide matters call the Samaritans on 08457 90 90 90 or visit
a local Samaritans branch or visit http://www.samaritans.or

Tributes poured in across social media for the comedy giant who was found dead in his California home on Monday

Celebrities used Twitter to wrote their heartfelt messages in the aftermath of the death of Robin Williams

'The funniest man in America': How Robin Williams' star continued to rise as the legendary comic fought his lifelong addiction demons

For laughs: Robin Williams performs at the 7th Annual Andre Agassi Charitable Foundation's Grand Slam for Children benefit concert on September 28, 2002 at the MGM Grand Hotel in Las Vegas, Nevada

One of America's most beloved entertainers Robin Williams, who was found dead Monday, will forever be remembered as a singular talent who rocketed to fame as a zany alien in Mork & Mindy and spent the next 35-plus years captivating millions with his incomparable gifts.

Born in Chicago in 1951, the four-time Oscar nominee and one-time winner started as a funnyman and soon proved he could also captivate America with his skills as an improvisor and dramatic actor.

He is survived by his wife of three years Susan Schneider and children Zachary Pym, 31; Zelda Rae, 25; and Cody Alan, 19.

Passed away: Robin Williams has died at the age of 63 at his Tiburon, California home after 35-plus years of entertaining millions

Despite his lifetime battle with depression and substance abuse, the four-time Oscar nominee was in the midst of a career Renaissance of sorts.

In December, Williams will reprise his role of Teddy Roosevelt in the third installment of the Night at the Museum franchise.

The Chicago-born funnyman had also recently made headlines after he signed on to once again play the cross-dressing Mrs. Doubtfire in a sequel to the 1993 family comedy.

Williams' star power and status as one of America's most adored comedians had never really gone away throughout his 35-plus year career.

He first became a household name in 1978 with his breakout role as alien come to earth Mork in the ABC comedy Mork & Mindy after debuting the role on Happy Days.

Partly on the power of his sitcom's popularity, Williams soon made his big screen debut in Robert Altman's 1980 comedy Popeye as the spinach-loving muscleman.

Rising star: Robin Williams' work in Mork & Mindy first made the Chicago native a household name

Dramatic chops: Williams quickly evolved from comedic TV star to big screen actor with dramatic chops. He would be nominated for four Academy Awards, winning one for 1998's Good Will Hunting alongside Hollywood novices Matt Damon and Ben Affleck

First Oscar nod: Pictured is a still from Williams' 1978 film Good Morning Vietnam, for which the actor would earn his first Oscar nod

 

Archive: A montage of Robin Williams' best movies

Little known start: While Mork & Mindy first brought the zany alien character fame, Williams had previously debuted the character in an episode of Happy Days

Reviews were mixed for the live action film, but Williams easily moved on to such successes as The World According to Garp, The Survivors and Moscow on the Hudson.

At 36, Williams took his career another great leap forward thanks to the undeniable magnetism he put on display in 1987's Good Morning Vietnam.

The role would win him his first Academy Award nomination. He would go on to receive three more nods and one statue, for his role of Sean Maguire in the 1998 hit Good Will Hunting alongside a fresh-faced Matt Damon.

He also played for tears in Awakenings, Dead Poets Society and What Dreams May Come, something that led New York Times critic Stephen Holden to once say he dreaded seeing the actor's 'Humpty Dumpty grin and crinkly moist eyes.'

Williams also won three Golden Globes, for Good Morning, Vietnam, Mrs. Doubtfire and The Fisher King.

Early days: Pictured here in his junior year at Michigan's .Detroit Country Day School, Williams was born in Chicago on July 21, 1951 and showed a talent for making people smile from an early age

Renaissance man: Eighth grade yearbook photos show the comedic genius also had an early penchant for sports

Williams was well known for his charitable spirit and work off screen with organizations like Comic Relief, the Christopher & Diana Reeve Foundation and St. Jude Children's Hospital.

Entertainment executive Jeff Katzenberg recalled his friend Williams' charitable work in an interview with the LA Times.

'There were so many ways and so many things he did for so many people,' Katzenberg told the Times in an interview. 'He really had just a giant heart and that's what makes me so sad.'

Along with Whoopi Goldberg and Billy Crystal, Williams started hosting an annual Comic Relief fundraising special to benefit the homeless in 1986.

He'd since helped to raise some $80 million for the charity.

Born in Chicago in 1951, Williams would remember himself as a shy kid who got some early laughs from his mother - by mimicking his grandmother. He opened up more in high school when he joined the drama club and he was accepted into the Juilliard Academy, where he had several classes in which he and Christopher Reeve were the only students and John Houseman was the teacher.

Charitable: Along with Whoopi Goldberg and Billy Crystal, Williams started hosting an annual Comic Relief fundraising special to benefit the homeless in 1986

Huge sum: Williams was well known for his charitable spirit and work off screen with organizations like Comic Relief, the Christopher & Diana Reeve Foundation and St. Jude Children's Hospital. He and co-hosts Whoopi Goldberg and Billy Crystal had raised some $80 million for Comic Relief since 1986

Thick and thin: Williams and Christopher Reeve became friends at Julliard and remained close for the rest of Reeve's life. After the Superman actor's paralyzing accident and eventual death, Williams would champion his family's charity

Encouraged by Houseman to pursue comedy, Williams identified with the wildest and angriest of performers: Jonathan Winters, Lenny Bruce, Richard Pryor, George Carlin. Their acts were not warm and lovable. They were just being themselves.

'You look at the world and see how scary it can be sometimes and still try to deal with the fear,' he told the AP in 1989. 'Comedy can deal with the fear and still not paralyze you or tell you that it's going away. You say, OK, you got certain choices here, you can laugh at them and then once you've laughed at them and you have expunged the demon, now you can deal with them. That's what I do when I do my act.'

Following Williams on stage, Billy Crystal once observed, was like trying to top the Civil War. In a 1993 interview with the AP, Williams recalled an appearance early in his career on 'The Tonight Show Starring Johnny Carson.' Bob Hope was also there.

'It was interesting,' Williams said. 'He was supposed to go on before me and I was supposed to follow him, and I had to go on before him because he was late. I don't think that made him happy. I don't think he was angry, but I don't think he was pleased.

Huge honor: Johnny Carson chose Robin Williams and Bette Midler as his last guests ever on The Tonight Show

Early days: Robin Williams and first wife Valerie Williams during Robin Williams After Saturday Night Live taping in New York City - November 11, 1978. Back then, Williams often partied with SNL star John Belushi

'I had been on the road and I came out, you know, gassed, and I killed and had a great time. Hope comes out and Johnny leans over and says, `Robin Williams, isn't he funny?' Hope says, 'Yeah, he's wild. But you know, Johnny, it's great to be back here with you.'

In 1992, Carson chose Williams and Bette Midler as his final guests.

Williams also could handle a script, when he felt like it, and also think on his feet. He ad-libbed in many of his films and was just as quick in person. During a media tour for 'Awakenings,' when director Penny Marshall mistakenly described the film as being set in a 'menstrual hospital,' instead of 'mental hospital,' Williams quickly stepped in and joked, 'It's a period piece.'

Winner of a Grammy in 2003 for best spoken comedy album, 'Robin Williams - Live 2002,' he once likened his act to the daily jogs he took across the Golden Gate Bridge. There were times he would look over the edge, one side of him pulling back in fear, the other insisting he could fly.

Played the angry Mickey: Robin Williams and Charles Fleischer present Richard Williams with the Special Achievement Academy Award for his groundbreaking animation on Who Framed Roger Rabbit in 1989

'You have an internal critic, an internal drive that says, `OK, you can do more.' Maybe that's what keeps you going,' Williams said. 'Maybe that's a demon. ... Some people say, `It's a muse.' No, it's not a muse! It's a demon! DO IT YOU BASTARD!! HAHAHAHAHAHAHA!!! THE LITTLE DEMON!!'

His undeniable success did not always bring Williams the happiness his gifts gave audiences.

Williams' drug and alcohol problems first arose while he was still appearing in Mork & Mindy--right at the start of his fame.

He had acknowledged drug and alcohol problems in the 1970s and `80s and was among the last to see John Belushi before the Saturday Night Live star died of a drug overdose in 1982.

Dark days: His divorce from his wife of 19 years and mother of two of his three children, film producer Marsha Garces, came a couple of years later and many outside his family's inner circle opening suspected his substance abuse struggles were to blame

He would later call the death of his good friend Belushi from cocaine and heroin overdose part of why he chose to go sober for the next 20 years.

'Was it a wake-up call? Oh yeah, on a huge level,' he once said.

His struggle would continue for decades. As recently as this past July, Williams would reconnect with the 12-step program he'd so often championed, this time during a brief stay at a Minnesota facility.

In 2006, Williams relapsed and described his family's reaction to the news in a September 2013 Parade Magazine interview:

'It was not an intervention so much as an ultimatum. Everyone kind of said, "You’ve got to do this." And I went, "Yeah, you’re right."'

His divorce from his wife of 19 years and mother of two of his three children, film producer Marsha Garces, came a couple of years later and many outside his family's inner circle opening suspected his substance abuse struggles were to blame.

The relapses, it seems, had happened before. In that same Parade interview, Williams described a 2003 relapse, which came after 20 years of sobriety, to the magazine:

'One day I walked into a store and saw a little bottle of Jack Daniel’s. And then that voice—I call it the lower power—goes, "Hey. Just a taste." Just one.’ I drank it, and there was that brief moment of "Oh, I’m okay!" But it escalated so quickly. Within a week I was buying so many bottles I sounded like a wind chime walking down the street. I knew it was really bad one Thanksgiving when I was so drunk they had to take me upstairs.'

Robins wed third wife, interior designer Susan Schneider, in October 2011.

Williams' final tweet was posted on July 31. He wished his daughter Zelda a happy 25th birthday.

Robin Williams married his third wife, now widow, Susan Schneider in 2011

Family: Williams was married to film producer Marsha Garces from 1989 until a surprise split in 2010. The two had a son Cody and daughter Zelda

Here, Williams, Garces and their children attend Universal Pictures' World Premiere of Man of the Year held at Grauman's Chinese Theatre in Hollywood

Williams' eldest son Zachary, left, with first wife Valerie Velardi is seen here attending the Comedy Awards in 2012