5. Shawn Ashmore's Iceman
Looking back at the Fox X-Men movies, it's shameful how the franchise treated Iceman. Rather than treating the character with respect and honoring his origin as one of the original X-Men, Iceman was treated as a secondary character. He never really was given a proper storyline nor did he get much character development over the course of the movies.
Despite a lack of materials, Shawn Ashmore still delivered an amazing performance working with the materials he was provided with. Now imagine what he could bring to the role with the X-Men in the hands of the MCU storytellers. We'd love to see Marvel bring Ashmore back as a more confident variant of the Bobby Drake we met in the Fox movies and perhaps even get the chance to see the character living as an out and proud hero in this universe.
As the Fox X-Men movies pre-date Bobby's coming out storyline in the comics, this was a thread the original movies didn't have the chance to adapt. However, Marvel now has the opportunity to celebrate Iceman and spotlight him as an openly gay hero within the MCU as it's high time the MCU added more diverse heroes into the mix.