Who he is: Wolverine, a.k.a. James Howlett, a.k.a. Logan
His power: Wolverine’s body quickly heals from injury and illness, making him effectively immortal. He has bone claws that retract from his knuckles; his strength, speed, and senses are enhanced; and his skeleton is coated with an indestructible metal.
His story: The X-franchise may be built on the conflict between Professor X and Magneto, but Wolverine is the breakout character. His pre-X-Men past is detailed in X-Men Origins: Wolverine, revealing that he was born James Howlett and ran away from home in 1845 after accidentally killing his birth father. James fights in the American Civil War, both World Wars, and the Vietnam War with his half-brother, Victor Creed, but seeks a life of solace after a brief stint with Col. William Stryker’s Team X. Creed and Stryker team up to manipulate Logan into undergoing the procedure that gives him his adamantium skeleton, and by the end of the movie, Logan is the amnesiac that meets Charles Xavier in X-Men.
The loner Wolverine learns to become a team player as he works with the X-Men to stop Magneto and save his new friend, Rogue, and he’s rewarded for his heroism with clues about his past. Logan digs deeper in X2, and the return of Stryker as the X-Men’s new threat begins to awaken new memories. He gets a few answers when he revisits the facility where the adamantium was bonded to his bones, but he loses the woman he’s fallen in love with when Jean Grey sacrifices herself to save her team. Jean’s death is only temporary, though, and she returns in X-Men: The Last Stand, now dominated by her ultrapowerful alternate personality, The Phoenix. Wolverine kills Jean when The Phoenix goes out of control, which sends him spiraling to a dark place, only seeing the light when he’s pulled out of the wilderness in The Wolverine and sent to visit an old acquaintance in Japan. He finds a new lover, a new sidekick, and a new lease on life in Japan, and he rejoins the X-Men two years later.