Piotr "Peter" Rasputin was born on a Soviet collective farm called the Ust-Ordynski Collective near Lake Baikal in Siberia. He lived there with his mother Alexandra, father Nikolai, and sister Illyana. His older brother, Mikhail, had been a Soviet cosmonaut and had apparently died in a rocket accident.

Peter's superhuman powers manifested during his adolescence while saving his sister from a runaway tractor. Immediately after, Peter was contacted by Professor Charles Xavier, the founder of the X-Men.

Peter was part of the second generation of X-Men, formed by Charles Xavier to save the original X-Men from the living island Krakoa. He agreed to leave the farm community in which he was born to go to the United States with Xavier. Xavier gave him the name "Colossus." After the battle was won, Colossus remained in the United States with the new X-Men.


Colossus is a mutant that has the ability to transform his entire body into a form of "organic steel", with properties similar to osmium but of still unknown composition. Colossus must transform his entire body into this armored state; he cannot transform only a portion of his body. When he transforms, he gains around a foot in height (official figures say about 7'5 feet tall in transformed state versus 6'6 feet in normal human form) and his weight is at least doubled. In his armored form, Colossus possesses superhuman levels of strength, as well as superhuman stamina and durability.

While in his armored form, Colossus requires no food, water, or even oxygen to sustain himself, and is extremely resistant to injury. He is capable of withstanding great impacts, large caliber bullets, falling from tremendous heights, electricity, and certain magical attacks. While he has great resistance to temperature extremes of hot and cold, extreme heat followed by rapid super-cooling has been shown to cause extreme damage.

Colossus is an excellent hand-to-hand combatant, having received training from Wolverine and Cyclops. He has had training in acrobatics and sword fighting from Nightcrawler. In his human form, he is exceptionally strong and fit, though not superhumanly so. He has completed college-level courses at Xavier's school.