In 1962—long before Wolverine and Cyclops were honing their mutant powers in “X-Men” (2000)—another set of mutant super-humans were helping the government fight crime. In “X-Men: First Class,” Charles Xavier (James McAvoy), Magneto (Michael Fassbender), Mystique (Jennifer Lawrence), Riptide (Álex González) and Beast (Nicholas Hoult) help the U.S. government stop an evil dictator from starting World War III.