The Incredible Hulk first hit comic book stands in 1962, but the character's source material is even older. Here are a few of his influences.
Frankenstein's monster: Not so much the 1818 book by Mary Wollstonecraft Shelley but more the 1931 film starring Boris Karloff. The Hulk was initially part of a spate of popular horror comics -- not super hero comics. And he looked very much like Karloff's monster: lumbering, stiff-limbed with a square head and bad bowl-cut. He has no costume, save for his green skin. (In the first comic, his skin was gray.)
Dr. Jekyll and Mr. Hyde: Dr. Bruce Banner initially would turn into the Hulk at night, like a werewolf, but soon writers decided that it would be more interesting to make him "hulk out" when he got angry. Interestingly, Dr. Jekyll will compete against the Hulk for box office supremacy this summer as a member of "The League of Extraordinary Gentlemen."
The atom bomb: Dr. Bruce Banner was transformed into the Hulk after getting too close to an exploding "gamma bomb," described in Hulk No. 1 as "the most awesome weapon ever created by man." This was 1962, after all, the year of the Cuban Missile Crisis. The early comics are rife with Cold War paranoia, fear of technology and Dr. Strangelove-style military caricatures.