Betsy Braddock
She is one of the children of Sir James Braddock, a champion of the Otherworld, another dimension who was sent to Earth by Merlyn to father a child to become Captain Britain. As her twin brother, Brian, became the superhero Captain Britain, Betsy developed telepathic powers when she reached her teenage years while in New York. She eventually joined the ranks of the X-Men under the nickname "Psylocke" after being rescued from Mojo and Spiral. She was his ally during several adventures and even replaced him as Captain Britain for a time, and is currently doing so after Brain become "Captain Avalon".