The Collaborative International Dictionary of English v.0.48:
Torturer \Tor"tur*er\ (t[^o]r"t[-u]r*[~e]r), n. One who tortures; a tormentor. [1913 Webster]WordNet (r) 3.0 (2006):
torturer n 1: someone who inflicts severe physical pain (usually for punishment or coercion)