Abbott and Costello Meet Frankenstein (1948)

Well, the title is pretty self explanatory. However, they also meet the Wolfman (Lon Chaney, jr.) and Dracula (Bela Lugosi) and one other famous character whose voice I'm sure you will recognize.

Trivia note: Frankenstein is played by Glen Strange, who also had a long running stint on Gunsmoke as Sam, the bartender, at Miss Kitty's Long Branch Saloon. Also, when the TV Lone Ranger appeared, he played the murderous Butch Cavendish, whose outlaw band ambushed and killed all but one member of the Texas Rangers squad tracking them, and, of course, that lone survivor became the Lone Ranger!