X-Men characters have been starring in movies since long before the Marvel Cinematic Universe (MCU), but that's not the only reason why they've been noticeably absent from the MCU. For decades, all the X-Men characters fans love were all owned by Fox, whereas the rest of the MCU was controlled by Disney. That all changed in December 2017, when Fox sold a huge portion of their company to Disney.
This acquisition means that the team of mutant superheroes can finally join the ranks of the MCU, and there are more than a few X-Men characters who should be in movies. Alternatively, it might be even more exciting to see some of the best X-Men characters rebooted in their own, stand-alone films. There's no shortage of movie ideas for fan-favorite X-Men, so Disney would be foolish to not capitalize on all the brilliant possibilities.