Witness true strength. Strength of will over others.
~ Drago Bludvist brainwashing Toothless to kill Hiccup.
Obey me, Waaario. I am your master, Mario is your enemy. [...] Don't let Mario get the six golden coins, don't let Mario reach the palace. [...] Obey Wario, DESTROY MARIO!!
~ Wario to the audience in an infamous advertisement for Super Mario Land 6: The 6 Golden Coins
With my magic, I can make every pony agree to work together! No arguments! No disagreements! I could ensure that every pony does precisely what they are supposed to do, with no distraction or delay! (Starlight Glimmer: Accord, you can't control ponies like that. My village was horrible! Everypony wanted to escape!) Then I will make sure they do not want to escape! You cannot make every pony the same. But I can make them all think the same way!
~ Accord to Starlight Glimmer, revealing his plan to brainwash the denizens of Equestria
Villains who 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.