Colossus (Piotr Nikolaievitch Rasputin) is a fictional character, a superhero in the Marvel Comics universe. Created by writer Len Wein and illustrator Dave Cockrum, he first appeared in Giant-Size X-Men #1 (May 1975). A Russian mutant, the character is a member of the X-Men, and is by far the physically strongest member of the team, being able to transform into a strong metallic form. Even without his powers he holds a physically imposing figure standing at 6' 7" (200 cm). Throughout the series he has been portrayed as a quiet, shy character, honest and innocent. He has had a fairly consistent presence in X-Men-related comic books since his debut. A talented artist, he only reluctantly agrees to use his powers in combat, feeling it is his responsibility to use his abilities for the betterment of human and mutant-kind.
Source: Wikipedia, "Colossus (comics)", available under the CC-BY-SA License.