The Collaborative International Dictionary of English v.0.48:

Hypnotist \Hyp"no*tist\, n.
   A person who hypnotizes another, especially one who is
   professionally trained in the technique.
   [PJC]

WordNet (r) 3.0 (2006):

hypnotist
    n 1: a person who induces hypnosis [syn: hypnotist,
         hypnotizer, hypnotiser, mesmerist, mesmerizer]