The Collaborative International Dictionary of English v.0.48:

Hypnotizer \Hyp"no*ti`zer\, n.
   One who hypnotizes; a hypnotist.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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