|Two men were known as Juggernaut. The original, and best known, is Cain Marko, a long time enemy and some times ally of the X-Men who must be imprisoned in mystic realms to halt his rampaging. After his father married his colleagues' wife, Cain constantly bullied his step-brother, Charles Xavier, angry that his father favored the gentle, smart Charles to his own son, and was in-turn abused by his alcoholic father regularly. After enlisting in the US army, Marko and Xavier found the Temple of Cyttorak in Korea, where Cain impulsively grabbed a glowing ruby from the lap of an idol and read the inscription "Whosoever touches this gem shall possess the power of the Crimson Bands of Cyttorak. Henceforth, you who read these words shall become forevermore a human juggernaut." The Gem's mystical power transformed Marko into Cyttorak's avatar on Earth, the Juggernaut. After years of being a villain and terrorist, Marko began to lose the powers of the Juggernaut, as he had become a hero and even joined his step-brother and his X-Men. After the releasing of the Asgardian God of Fear, seven divine hammers were sent to Earth, searching for the Worthy. Marko, who had since become a member of the Thunderbolts, became Kuurth Breaker of Stone and Cyttorak granted his power to the X-Man Colossus. Eventually, Marko became Cyttorak's avatar once again and gained even greater strength.
Due to his close association with step-brother Charles Xavier, his encounters with mutant heroes such as the X-Men, his affiliation with the X-Men, Excalibur, Black Tom Cassidy and the Brotherhood of Evil Mutants, Juggernaut is often considered a mutant himself on Earth-616, and is in fact also sometimes truly a mutant in some realities. This is possibly also due to lack of research from the authors.|