As one of the most recognizable villains in comics, Cain Marko has had a long history of terrorizing the X-Men with his massive frame and incredible strength. Powered with the Gem of Cytorrak, Juggernaut launched his first attack on the X-Men in an attempt to murder
his step-brother, Professor Charles Xavier, a person he blamed for many of the hardships he endured as a child. After being defeated, Juggernaut allowed his hate and anger to drive him to commit even more acts of violence against Xavier and his students.
After years of being characterized as a bully who thrives off taking pleasure from others' pain, Juggernaut's image began to change in the early 2000s as he and his friend Black Tom joined the X-Men as part of a plan to destroy the team from the inside. When Black Tom betrayed him, Juggernaut considered taking a different path and stayed with the X-Men. He's also served with the Thunderbolts under Luke Cage.