Aldebaran (real name unknown), commonly known simply as Al, is a major anti-hero in the 2014 Japanese dark fantasy light novel series Re:Zero − Starting Life in Another World, as well as its anime television series & manga adaptations of the same name. He also appears in various related works, including video games and short stories all based in the narrative universe of Re:Zero.

Eighteen years ago, the man known as “Aldebaran” was transported from Earth to another world. This new world, which was technologically and culturally reminiscent of the middle ages, was full of magic and strange creatures often seen in fantasy fiction. Shortly after arriving in the world, Aldebaran lost his arm and served as a gladiator in the Empire of Volakia. After spending ten years fighting as a slave of the sword, Aldebaran escaped captivity.