The Collaborative International Dictionary of English v.0.48:

Tormentor \Tor*ment"or\, n.
   1. One who, or that which, torments; one who inflicts penal
      anguish or tortures. --Jer. Taylor.
      [1913 Webster]

            Thoughts, my tormentors, armed with deadly stings.
                                                  --Milton.
      [1913 Webster]

   2. (Agric.) An implement for reducing a stiff soil,
      resembling a harrow, but running upon wheels. --Hebert.
      [1913 Webster]

WordNet (r) 3.0 (2006):

tormentor
    n 1: someone who torments [syn: tormentor, tormenter,
         persecutor]
    2: a flat at each side of the stage to prevent the audience from
       seeing into the wings [syn: tormenter, tormentor,
       teaser]

Moby Thesaurus II by Grady Ward, 1.0:

49 Moby Thesaurus words for "tormentor":
   act drop, annoyer, asbestos, asbestos board, backdrop, badgerer,
   batten, border, bully, cloth, coulisse, counterweight, curtain,
   curtain board, cyclorama, decor, drop, drop curtain, fire curtain,
   flat, flipper, hanging, harasser, harrier, heckler, nag, nudnik,
   nudzh, persecutor, pest, pesterer, plaguer, rag, sadist, scene,
   scenery, screen, side scene, stage screw, tab, tableau, tease,
   teaser, torment, transformation, transformation scene, wing,
   wingcut, woodcut