Guards! Throw these miniscule vermin into the dungeon until they are of worthier size!
~ King Goobot

Gaolers (also called Wardens or Jailers) are known for keeping prisoners in check. These villains are feared for, or are known to, imprison their captives, whether it is in a jail cell, a cage, etc.

Some gaolers can be prisoners themselves, like the Black Mouth.

NOTE: Some of these villains may be Pure Evil, such as Scar, Ego, Lots-O' Huggin' Bear, Jerome Valeska, Judge Claude Frollo and Bill Cipher