When did the Hulk first appear in a comic book?

It's hard to believe, but before there was Smart Hulk the original big green guy had a bit of a stuttered start on his way to pop-culture stardom.

The original series didn't last long, but after Stan Lee and Jack Kirby found out a college had named their mascot after him, they realized they had something special with Hulk.

And that's why today you get to enjoy a plethora of Hulk-themed movies, shows, comics, merch, toys, and so much more. But when did he first appear in one of Marvel's comic books?

Click START to answer.