Cain Marko is a human juggernaut. Once he begins moving in a certain direction, no power on Earth can stand in his way. Scientists would classify him as an "irresistible force" -- and when he gets a head of steam, there's no object he can't move. A mystically empowered human, Juggernaut has long harbored resentment toward his stepbrother, Charles Xavier -- the telepathic, telekinetic mentor of the masked, mutant X-Men. He has clashed with his stepbrother's heroic charges repeatedly through the years -- but on occasion, he's also been called upon to save the universe!

Real name: Cain Marko
Occupation: Professional criminal
Group affiliation: Frequent partner of Black Tom Cassidy
Base of operations: Mobile
First appearance: X-Men (Vol. 1) #12 (1965)

Height: 6'10"
Weight: 900 lbs.
Eye color: Blue
Hair color: Red

Powers: The Juggernaut possesses untold power, mystical in nature, which enhances his strength and grants him an extraordinary degree of resistance to all forms of injury. Once he begins moving in a certain direction, no force on Earth can stop him -- only slow his pace. Sustained by the Crimson Gem of Cyttorak, Cain Marko can survive indefinitely without food, water or oxygen. However, Juggernaut is vulnerable to magical forces of sufficient strength. Without his helmet, constructed of an unknown mystical metal, he is susceptible to psionic attack.

Weapons: None

History: Cain Marko has wasted his entire adult life attempting to escape the shadow of his stepbrother, Professor Charles Xavier. Cain's father -- Dr. Kurt Marko, an atomic researcher -- married the widow of his colleague, Dr. Brian Xavier, presumably for her wealth. He took up residence in the family's Westchester mansion with Sharon Xavier and her young son -- Charles, a fledgling mutant telepath. Cain, who had become a cruel and spiteful boy, came to live with them shortly thereafter.

Cain grew to hate his new stepbrother, mostly because his father favored Charles, and took to bullying the younger boy. As punishment, his father secretly beat him. But Cain did not suffer the abuse alone. Inexperienced at the use of his burgeoning abilities, Charles could not control or terminate his contact with Cain's mind during these periods of pain. Cain somehow sensed that Charles had invaded his thoughts and came to regard his stepbrother as an enemy.

Drafted into military service, Cain was attached to the same unit as Charles. When Cain deserted under fire, Charles pursued. He hoped to convince his stepbrother to return of his own accord. Charles followed Cain into a cave that housed the lost temple of Cyttorak, a powerful mystical entity. Lured by greed and delusions of grandeur, Cain unearthed a large red ruby. Empowered by the Crimson Gem of Cyttorak, he stood transformed into a human juggernaut.

Lacking his stepbrother's moral fiber, Juggernaut turned his newfound strength against Charles and his masked X-Men -- a handful of troubled teenagers learning to control their mutant powers...and fighting to preserve their mentor's dream of peaceful coexistence between the two species of man. Each time they clashed, the heroes managed to beat back his bull rush. Often, Juggernaut worked with the energy-emitting mutant terrorist named Black Tom Cassidy, whom he befriended while in prison.

The sentient psionic being known as Onslaught -- actually an amalgamation of the psyches of Xavier and Magneto, would-be world conqueror and mutant Master of Magnetism -- ripped the Crimson Gem of Cyttorak from Juggernaut's body and imprisoned him within. Inside the jewel, Cain learned he was an avatar for Cyttorak. As such, the otherworldly entity sought to assume control of Juggernaut's form. But Cain, through sheer force of will, destroyed the evil god and returned to Earth -- stronger than ever, but unable to fully control his amplified abilities.

Cyttorak was merely one of a pantheon of eight gods, all with earthbound avatars. These Exemplars enlisted the Juggernaut's aid in constructing a machine that would enslave the human race. As the Exemplars tended to in their final preparations, Cain withdrew deep into himself, where he clashed with Cytorrak. Charles entered his stepbrother's mind to aid him in the battle, but the Exemplar known as Bedlam sensed his presence and expelled him. Still, Charles' short stay in Juggernaut's head had helped Cain regain control of his psyche. After defeating Cyttorak, Juggernaut destroyed the Exemplars' God Machine. He then turned his attention to the avatars themselves, defeating each in turn.

Juggernaut again was cast as a hero when the sentient spaceship Prosh escaped the confines of a Celestial prison, returned to Earth and dispatched a group of disparate beings on a journey through time to uncover the keys to preserving human evolution. Besides Cain, Prosh's task force included Phoenix and Iceman, members of the X-Men; and Mystique and Toad, mutant terrorists. Their mission: Save the human race from a threat that might not manifest itself for millions of years. Juggernaut was shown that for all his physical strength, he long has lacked strength of character. Despite all his yearning for power, he has squandered his supernaturally enhanced abilities. When Prosh reassembled the members of his team in the present, they fought and defeated the enigmatic alien entity known as the Stranger, who sought to control the natural evolution of humans and mutants. If not acquiring a newfound respect for life and human dignity, at least Juggernaut gained a better sense of understanding for the mutant plight.