Quicksilver, whose real name is Pietro Maximoff, is a superhero known for his incredible speed. As a mutant, Pietro can move, think, and react at supersonic velocities, making him one of the fastest characters in the Marvel universe. He is often portrayed as a complex character with a mix of heroism and selfishness, reflecting his troubled past and strained relationships, particularly with his twin sister, Wanda Maximoff (the Scarlet Witch). His speed powers and dynamic personality make him a notable figure in both the X-Men and Avengers storylines.