8. Psylocke
Psylocke was one of many classic mutant characters who was crammed into The Last Stand (as one of Callisto's relatively anonymous gang), despite not having any substantial screen time whatsoever nor even possessing many of the characteristics of her comic counterpart (thanks again, Brett Ratner). It's evident that she deserves
actual scenes dedicated to her, something Days of Future Past could remedy, especially considering she does exist in that comic arc. Given how keen Bryan Singer seems to be keen to just disregard a lot of Ratner's film - the pick and choose approach is probably best here - it might make sense to just start Psylocke again from scratch; actually develop her as a character and give her all of the traits she has in the comics. A strong telepath, this could set the stage for a stellar showdown of wits between herself and Emma Frost, given that Frost was freed by Magneto at the end of the last film. These new films could definitely use more ass-kicking femmes, and Psylocke is just the character.