Since the beginning of cinema, many filmmakers have been fond of using mirrors to create artistic, moving stills and scenes. There's more to looks and reflections in images, after all.
When the protagonist or character has the reflection in the mirror -- it could mean several things; perhaps introspection, another perspective or side of the character, a reflection of the innate self, or a reveal of a mystery.
From old films to now, here's how filmmakers used mirrors in their works.
Preview image was taken from the video.