Quicksilver (Pietro Maximoff) is a mutant comic book superhero in the Marvel Comics universe, his superhuman ability being super-speed and reflexes. Created by Stan Lee and Jack Kirby, he first appeared in X-Men #4 (1962).

Quicksilver is the brother of the Scarlet Witch and the son of Magneto, although this latter fact was not known for many years. The siblings were initially super-villain members of Magneto's Brotherhood of Evil Mutants, but they soon reformed and joined The Avengers. Quicksilver was later a member of the team X Factor for a short time when he was at odds with the Avengers. He was married to Crystal of the Inhumans and their pair had a daughter, Luna.

Quicksilver possesses the superhuman ability to run, think and react at great speed. He is even able to fly for short distances. In this regard, he is a counterpart to DC Comics' The Flash.