We're all familiar with Marvel's big green force of nature, but over the years there's been a whole rainbow of Hulks.

But, as it would turn out, the grey coloring was difficult for Marvel's printers to produce, so Lee was forced to shift the Hulks appearance from grey to green in The Incredible Hulk #2.

The famous Green Hulk and the new Red Hulk have a lot in common, but also some key differences in the comics and MCU.