Captain America: The Winter Soldier (2014)
Peter (Pietro) Maximoff, also known as Quicksilver is a mutant with the ability to move and think at superhuman speeds. His sister is Scarlet Witch. Quicksilver joins up with Ultron to avenge the death of his parents and his belief that Tony Stark was responsible.
The Avengers: Age of Ultron (2015)
Quicksilver joins the Avengers in the battle against Ultron.