According to Kirby, his inspiration for The Hulk came from, well, a rather incredible feat of bravery that he witnessed. As Kirby revealed to The Comics Journal in an interview (which i09 unearthed), he once saw a mother lift up a car that had pinned a baby down. The trauma, Kirby thought, imbued a superhuman level of strength in the mother, which allowed her to lift the car. Obviously, this sounds a little similar to the Hulk's routine, wherein Bruce Banner transforms into the all-powerful Hulk during moments of extreme stress or duress.
Here's how the King explained it:
GROTH: The next character, if I remember correctly, was The Hulk. If I remember correctly you drew a six-issue run of that, then it was cancelled for a little while, then Steve Ditko started it in an anthology book called Tales to Astonish. Can you talk a little bit about how you were involved in creating The Hulk?
KIRBY: The Hulk I created when I saw a woman lift a car. Her baby was caught under the running board of this car. The little child was playing in the gutter and he was crawling from the gutter onto the sidewalk under the running board of this car — he was playing in the gutter. His mother was horrified. She looked from the rear window of the car, and this woman in desperation lifted the rear end of the car. It suddenly came to me that in desperation we can all do that — we can knock down walls, we can go berserk, which we do. You know what happens when we're in a rage — you can tear a house down. I created a character who did all that and called him the Hulk. I inserted him in a lot of the stories I was doing. Whatever the Hulk was at the beginning I got from that incident. A character to me can't be contrived. I don't like to contrive characters. They have to have an element of truth. This woman proved to me that the ordinary person in desperate circumstances can transcend himself and do things that he wouldn't ordinarily do. I've done it myself. I've bent steel.
It's not clear how Stan Lee, who is credited as Hulk's other co-creator, factored into the creative process, but it seems that Kirby's contributions had a solid foundation to work off of.
What do you think of Kirby's Hulk origin story? Let us know in the comments.