Psylocke was a mutant telepath. In the Original Timline she was a member of Callisto's Omega Gang, a group of mutant outcasts based in an underground network in the United States. In the Revised Timeline, she's the second Four Horsemen of The Apocalypse. She appears as a minor villainess in X-Men: The Last Stand and appears as one of the secondary antagonists in X-Men: Apocalypse.
She is played by Mei Melançon in X-Men: The Last Stand and by Olivia Munn in X-Men: Apocalypse.
When the mutant cure was created, Psylocke and the Omegas protested, saying that there was nothing wrong with mutants and therefore, nothing to cure. Callisto decided to join Magneto's Brotherhood of Mutants. The rest of her group, which included Psylocke, Quill, and Arclight, followed, and became leading members of the Brotherhood.
Psylocke and the Omegas fought in the battle on Alcatraz Island, where she, Quill, and Arclight entered Worthington Labs while the rest of the mutants fought outside. Psylocke captured Warren Worthington, and attempted to kill him by throwing him off the balcony, but his son saved him before he could hit the ground. When Phoenix began to destroy Worthington Labs with her disintegration wave, Psylocke tried to escape the building but was killed.
Psylocke appeared in X-Men: Apocalypse as the one of the two quaternary antagonists of the film along with Archangel. She is played by Olivia Munn. Munn was initially offered the role of Vanessa in the film Deadpool, but she was disinterested in playing the role of the girlfriend. However, Kinberg wanted her to have a role in the X-Men film universe so much that he and director Bryan Singer approached her with the role of Psylocke a few weeks later.