The Marvel Cinematic Universe (MCU) has slowly increased the slate of mutants appearing in the Multiverse Saga, but each mutant has varying levels of power. When the MCU first began in 2008 with Iron Man, the rights to the mutants, and Marvel's most famous mutant team of heroes, the X-Men, was still held by Fox. As a result, the MCU had to avoid any mention of mutants until much more recently.