Brainwashers can take complete control of other people to do their bidding, either through magic, psychic power, or hypnosis. The victim then becomes the villain's helpless puppet and most often becomes a de facto villain falling under the "Possessed/Brainwashed" category. Some villains can also brainwash their victims through complex manipulation and intense charisma, to the point of making their followers absolutely devoted to them and ready to commit the worst upon order. (To them only, not to an ideology.)
A Brainwasher differs from a Possessor by the fact that he or she does not need to enter the victim's body to take control, and from a Corrupting Influence for the victim has its spirit eclipsed instead of turning evil, though the outcome is quite similar in all cases.