As the heroes prepare to assemble, we look back on previous films
'X-Men: First Class'
'nuff said: Producer Bryan Singer and 20th Century turned back the clock with this youth-heavy reboot, showing the beginnings of the team and exploring the dual natures of Professor X (James McAvoy) and Magneto (Michael Fassbender). A few "X-Men" vets made cameo appearances.
Worldwide box office: $340+ and counting.