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.