tormentor

Short definition from Wiktionary

Noun

1. 1
   One who torments; a person, animal, or object that causes suffering.
2. 2
   One who torments; a person, animal, or object that causes suffering: A person delegated to torture prisoners.
3. 3
   Something abstract that causes suffering.
4. 4
   One of a pair of narrow curtains just behind the front curtain and teaser that mask the areas on the sides of the stage and can be adjusted to the desired width.
5. 5
   An implement for reducing a stiff soil, resembling a harrow, but running upon wheels.
6. 6
   A long meat-fork.