First Steps introduces the world to Mister Fantastic, Invisible Woman, Human Torch and The Thing, but there's one other character of importance.

First Steps will introduce one of the comic's mightiest characters, who Kevin Feige says has a bright MCU future.

How Franklin Richards, the power cosmic and Doctor Doom's appearance in "The Fantastic Four: First Steps" credit scene affects "Avengers: Doomsday."

In a 1982 arc by John Byrne, Franklin gets frustrated trying to solve a Rubik’s Cube and uses his powers to age himself into an adult body, though he couldn’t actually gain more emotional maturity. He winds up going back to being a kid, placing restrictions on his own abilities to allow him to have something of a normal childhood.

EXCLUSIVE: Marvel Studios president Kevin Feige reveals why Franklin Richards was introduced in the MCU's first Fantastic Four movie.

In Marvel Comics, Doom’s fixation on Franklin is legendary. He views the boy’s near-limitless powers as the key to creating and ruling Battleworld, a twisted reality of his own making as seen in Secret Wars.

Franklin’s powers allowed him to create the universe, dimensions, avoid mind control, and every other cool power you can think of. Franklin Richards is considered a Beyond Omega Level mutant, and he is the only one in that category, making him the most powerful mutant on Earth.