Mind control

The whumpee now doesn't have full control of their actions, thoughts and/or body, oh no! *excited face*

A cursed or magical object, a spell or potion, someone's power, the sources for such situation are vast, and so are the possibilities for what they will make the poor whumpee do.

Although similar, we'll treat this trope and "possessed" as diferent cases.

TV Shows
Merlin


 * 1x07: A Sidhe uses magic on Arthur (Bradley James) to make him "fall in love" with her, so she can later sacrifice him (the soul of a human prince) to open the gates of Avalon. Mind controled Arthur is shown without expression and repeating her every word in a haze, obeying her every sugestion.

The Flash


 * 1x08: A meta capable of "enhance" people's emotions to the point where they're controled by it, brings out all of Barry's anger. Barry lashes out with everyone and gets multiple arrow wounds from Oliver Queen, who is trying to bring him back into sense.