Lon Chaney Jr. Son Of Dracula (1943)
Bela Lugosi was not the first choice for the Master of Darkness in 1931; Dracula director Tod Browning was set on casting silent film star Lon Chaney. Sadly, Chaney died before filming started, and Lugosi was eventually cast in his place.
So it's all rather fitting that for the final part of Universal's Dracula triptych, Son Of Dracula (the second part was Dracula's Daughter in 1936) the vampire's cloak was donned by the actual son of the first choice: Lon Chaney Jr., who is the only actor to have played all four classic horror creatures, including the Wolf Man, Frankenstein's Monster, and the Mummy.
Son of Dracula sees the mysterious Count Alucard (read it backwards; the "Son" in the title is a trifle deceptive) arrive in New Orleans, marry into a plantation family, and run his usual amok. Importantly, it's the first film to show the vampire transforming into a bat on screen; previous incarnations had that happen safely out of sight, where they could use much less prosthetic make up.
Watch the Son of Dracula trailer.