X3: Juggernaut first surfaced on the same prison truck that was transporting Mystique to a special facility. He had been captured and locked into a coffin-like chamber that prevented him from moving at all. Magneto came to Mystique's rescue during transport, and freed Juggernaut as well, who promptly joined his cause against the mutant cure. Juggernaut followed Magneto on several other missions, including trying to recruit the newly resurrected Jean Grey, where Juggernaut fought Wolverine while Magneto and Xavier pleaded with her.
When Magneto decided to take the fight for his cause directly to the Worthington Laboratories, he charged Juggernaut with killing the young mutant Leech, who was the source of the mutant cure. Juggernaut charged into the facility, but was followed by the young X-Man Kitty Pryde, who phased him into the floor. This only held him for a short while, and then he gave chase to her through the facility, crashing through walls shortly after she phased through them. She managed to elude him and find Leech herself, but could not use her powers and escape around Leech, but managed to trick Juggernaut into charging them, and when he got to close, Leech removed his power, and Cain hit the wall hard, knocking himself out. What happened to Juggernaut afterwards is unknown.
888