Japanese term that means a magical being, i.e. a genie or sorcerer. It can also refer to a demonic or evil entity.

In the manga/anime Dragon Ball Z, Majin (D'jin in the Viz manga) is the title given to someone under the control of the Wizard Babidi. When someone is Majin, an "M" appears on their body (usually on the forehead, or in Yakon's case, the chest). When someone becomes a Majin, Babidi uses his magic to increase the evil inside their hearts so much that it takes control of their character, and allows them to be controlled by him.

a stone warrior deity that is believed to come to life and kick righteous ass when the faithful are messed with, so you know where this is going