Like Christian Bale, Jake Gyllenhaal is an actor who's happy to customize his appearance to make himself suitable for a movie role. When his part in 2014's 'Everest' called on him to have long hair, Gyllenhaal had no reservations about obliging.
We have some reservations, though. No matter how long your hair becomes, we're not convinced it's ever acceptable to wear it as a man bun. Not even Gyllenhaal can get away with that! Perhaps he realized - he cut it off as soon as filming was over.