Quicksilver (Pietro Maximoff) is a fictional character appearing in American comic books published by Marvel Comics. The character first appeared in the comic book X-Men #4 (March 1964) and was created by Stan Lee and Jack Kirby. The character has since starred in two self-titled limited series, and has historically been depicted as a regular team member in superhero title The Avengers. Quicksilver has the superhuman ability to move at great speeds. In most depictions, he is a mutant, a human born with innate superhuman powers. In comic book stories beginning in 2015, he is the product of genetic experimentation by the High Evolutionary. Quicksilver most commonly appears in fiction associated with the X-Men, having been introduced as an adversary for the superhero team. In later stories, he became a superhero himself. He is the twin brother of the Scarlet Witch and, in most depictions, the son of Magneto and the half-brother of Polaris.