Actor Mark Ruffalo became the definitive Hulk of the MCU after the franchise failed at trying its hand with Edward Norton in The Incredible Hulk. The actor made his MCU debut with The Avengers, after which he appeared in multiple titles, including Thor: Ragnarok and She-Hulk: Attorney At Law. However, he has yet to receive a solo film.

One of the defining characteristics of the Hulk is his green skin color. As a result of his exposure to gamma radiations, the green has been his most defining quality and has even led to him being given multiple monickers. Comic book legend, Stan Lee, who created the character, however, reportedly initially wanted the character to be grey.

Mark Ruffalo’s Superhero Became Green Due to a Technical Issue

‘The Green Goliath’, ‘The Jolly Green Giant’, and the ‘Green Machine’ are just some of the nicknames that the Hulk is referred to in the Marvel comics. Played by Mark Ruffalo in the MCU, the character is known for his extreme rage. The character is powerful enough to destroy every obstacle in his wake. In his alter-ego, the Hulk is a genius scientist named Dr. Bruce Banner.

Green has become a staple characteristic of the Hulk, with every iteration portraying him as a green monster. However, the most distinctive feature of Hulk was reportedly not part of the initial design. Stan Lee, the creator of various heroes such as Spider-Man, Iron Man, Captain America, and more, revealed that the first version of the Hulk was grey.

Talking about it in an interview, the Marvel legend mentioned that the green color came from the printer’s inability to print grey in a consistent fashion. He said,

I did not think of green originally, I made it grey in the first issue. I thought that will be scary-looking, a guy with grey skin. But unfortunately, when the book came out the grey was a different shade on every page. One page was light grey, one page it was dark grey, on some pages, he looked almost black, one page it was white. 

And I realized the printer was having trouble with the grey color. So when you’re a cartoon editor and writer you’re like God, you can do anything. I said: ‘I’ll change his skin color’. So in the next issue, I made him green. 

Lee mentioned that he consulted the person in charge of the printer, and he recommended any color that was not grey, so he chose green. The writer also mentioned that the green helped him come up with various monickers for the Hulk.

Stan Lee Was Inspired By Two Major Literary Figures For The Hulk

One of the most important character arcs of Mark Ruffalo’s Hulk in the MCU is his struggle for balance between his moralistic human self and the rageful monster that he becomes when he is angry. Ruffalo has many moments in the films where he is troubled by the aspect of committing crimes and destroying lives. He goes to dark places in his mind as well.

This depth in the character was brought about by two important inspirations for Stan Lee. The comic book legend was reportedly inspired by the literary classics Frankenstein and Dr. Jekyll and Mr. Hyde in creating an alter-ego that brought out the worst parts of a person. He said in an interview,

I always liked Jekyll and Hyde, and I always liked the Frankenstein movie — the old one with Karloff. And in the Frankenstein movie, I always felt the monster is really the good guy. He didn’t want to hurt anybody. All those idiots with torches were always chasing him up and down the hills. 

So I thought it would be fun to get a monster who was really a good guy, but nobody knew that, and to take a leaf from the Jekyll and Hyde thing where he could change from a normal person into the monster. And I did The Hulk.

Though this story is a bit in conflict with artist Jack Kirby’s anecdote about being inspired to create the Hulk after seeing a mother lift a car to save her baby (via The Comic Journal), Stan Lee’s inspirations are obvious when Hulk is seen in that lens.