Keeper

Keeper may mean:

A curator as, for example, at the British Museum
A menstrual cup
In some sports, a player who protects a goal, see Goalkeeper
A warder or guardian
A gamekeeper
A term used to refer to the status of a person that one is dating being worth marrying.
In the universe of Babylon 5, a Keeper is a small parasitic creature employed by the Drakh to control other beings. A Keeper will graft itself onto a victim and control that person's actions as the Drakh dictate. Large amounts of alcohol will put a Keeper to sleep, but only the death of the controlling Drakh will actually kill the Keeper, which can regenerate and grow back if forcibly removed.