Said to be as strong as Sonic is fast, Knuckles the Echidna can always be relied on to help. He and Sonic don't always get on, but they are ultimately good friends. Knuckles can be a bit of a loner, which may explain why he is so naive and gullible, and easily tricked by Dr. Eggman. Although it's also been put that Knuckles believes there is good in everyone and hence can be very trusting.
Knuckles first punched his way into Sonic's life in Sonic the Hedgehog 3, where he's introduced as the last surviving member of the Knuckles Warrior Clan and is responsible for guarding Angel Island's Master Emerald.
Knuckles has a unique weapon: his super-strength spiked knuckles, which quickly earn him the reputation for being the physically strongest Sonic character. A martial arts pro, he is able to punch through thick steel, lift objects many times his size and weight and shatter huge boulders to smithereens. His fiery temper is reflected in his flame-red dreadlock-like spines, which give him the added ability to glide. If necessary, hes always happy to take the plunge and swim - and he can burrow like a gopher.
The ongoing conflict between Knuckles and Sonic in games, comics and TV shows has led to some of the most clichéd scenes of the series, in which their petty bickering quickly turns to fisticuffs. Fortunately for their friendship, they are always interrupted (thus it is never revealed which is the more powerful of the two). But, despite their differences, they always join forces when evil is near.
Echidna is the scientific name for a spiny anteater - which may be the reason why it is rumoured that Knuckles' favourite food is ant burgers. Actually, it's fruit.