X-Men: Apocalypse - Every Character Ranked From Worst To Best

She might well look the part for a certain type of comic book fan who doesn't question why the other Horsemen get helpful armour and she gets a bathing suit, but you can absolutely tell that Psylocke was a late addition to the film.

Bryan Singer and Simon Kinberg admitted that they had no plans for Psylocke to be the fourth Horseman until they realised their initial outline made no sense. From there Olivia Munn was cast (because - partly - she looked the part in some fan art they saw online), and apparently nobody bothered to really write her a decent part.

There might be lots of promise here (and hopefully she does get to join X-Force with Deadpool) but Psylocke is mostly relegated to standing around sneering. She's a terrible bodyguard to Caliban and while she helps find Angel, there is no explanation of how she knows he exists (let alone where he is), suggesting Apocalypse was initially supposed to use Caliban to find his Horsemen until she arrived to mess the plot up.

She did get one bad-!*$% moment of combat (ruined unnecessarily by the trailer), but Psylocke just sort of skulking off before the credits says all you need to know about how important she is to the plot.