Also known as Elizabeth 'Betsy' Braddock, Psylocke in the comics is the child of James Braddock Sr., who came from the alternate dimension Otherworld and fathered three kids. Elizabeth suffered an early trauma when she was blinded and nearly killed by a villain, before being given artificial eyes. Her powers include telekinesis, particularly focusing that energy into a "psychic knife" to use on adversaries, plus impressive martial arts skills. How much of her Marvel backstory will be filtered into the movie is something that we will have to wait and see.
Her casting comes just days after it was announced that EastEnders' Ben Hardy is set to play Angel in the film.
With a script from X-Men: Days Of Future Past's (2014) Simon Kinberg plus Singer stalwarts Michael Dougherty and Dan Harris (X-Men 2), X-Men: Apocalypse is set in the 1980s and finds Xavier (James McAvoy), Magneto (Michael Fassbender), Mystique (Jennifer Lawrence) and Beast (Nicholas Hoult) facing off against massively powerful mutant Apocalypse (Oscar Isaac) alongside younger versions of Jean Grey (Sophie Turner), Scott 'Cyclops' Summers (Tye Sheridan), Ororo 'Storm' Munroe (Alexandra Shipp), Nightcrawler (Kodi Smit-McPhee) and Jubilee (Lana Condor).
Rose Byrne (X-Men: First Class) is back as Moira MacTaggert, and there will be appearances from Hugh Jackman's Wolverine and, reportedly, the older Magneto, played as usual by Ian McKellen.
X-Men: Apocalypse is due out on 19 May 2016.