The one person we didn’t know was Psylocke, and the reason why is because originally in the script we sort of…
Olivia Munn officially signed on to X-Men: Apocalypse in mid-April 2015 – rounding out the Four Horseman team just a couple weeks before production later that same month.
In the film, this group consists of Magneto (Michael Fassbender), Storm (Alexandra Shipp), Angel (Ben Hardy) and Psylocke (Olivia Munn), but that wasn’t always the case.
In fact, most early drafts actually only included three of those Horsemen, with Psylocke only entering the fray late in the screenwriting process.