Doctor Doom's reign of terror is just beginning. Here's what to know about his role in the upcoming movie, 'Avengers: Doomsday,' including cast, release date and potential plot.

Credit: Marvel Studios In their MCU debut, the Fantastic Four become a Fantastic Five with the arrival of Reed and Sue's son, Franklin Richards. Worries that he might not be "normal" are confirmed in Fantastic Four: First Steps when Galactus recognises that the boy can wield an unlimited energy known as the Power Cosmic (presumably because of the "cosmically compromised DNA" shared by both of his parents).