The original Fox X-Men franchise had some of the absolute best castings of all time, and 20 years after their final battle, Avengers: Doomsday is bringing them all back. The Marvel Cinematic Universe (MCU) began in 2008, two years after X-Men: The Last Stand wrapped up. In that final confrontation between legendary heroes and villains like Magneto and Professor X, the franchise appeared to take its final bow.