One of the biggest mysteries surrounding the titular Mandalorian in Disney+'s Star Wars franchise. Hailing from the planet Mandalore, the Mandalorians are a unique breed of warriors who have wielded ancient weapons, crafted incredibly strong armor, and defeated notable foes. All of this extends in some way into The Mandalorian show.
It's been confirmed that the main character was a foundling - an orphan - who was taken in by the Mandalorians after his parents were killed during the Clone Wars. A handful of flashback scenes from the first few episodes of The Mandalorian showcase some sort of droid attack on the Mandalorian's homeworld. Whether that planet is Mandalore and if the attack was really the Siege of Mandalore remains to be seen, but regardless, at some point after the attack, the young child was rescued by the Mandalorians and later assimilated into their culture. Since then, he hasn't taken off his helmet. Sort of.
About midway through The Mandalorian episode 4, "Sanctuary", the This is the way." Shortly after this conversation, the Mandalorian removes his helmet off-screen so that he can eat, but no one else is around to see his face. This solves a mystery about the main character and the Mandalorian culture but brings up another question.
In the previous episode, "The Mandalorian series, Mandalorians do remove their helmets when they are alone but never when they are in the company of others, possibly even people they are close with.
Given that the Mandalorian culture is one of pride and honor, nothing physical happens to them when they remove their helmets in front of someone else. Instead, they lose the privilege of putting it on again. This is what the Mandalorian tells Cara Dune towards the end of the episode, which she appeared to believe was a bit ridiculous. To some, it may be an anti-climactic reason for Mandalorians constantly wearing their helmets, but once again, knowing their culture, it's actually understandable.
Right now, Pedro Pascal's face as the Mandalorian. While there's no answer for that question yet, the show hasn't wasted any time in setting up the possibility down the line.