The Collaborative International Dictionary of English v.0.48:

Mesmerizer \Mes"mer*i`zer\, n.
   One who mesmerizes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

47 Moby Thesaurus words for "mesmerizer":
   Artful Dodger, Casanova, Don Juan, Machiavel, Machiavelli,
   Machiavellian, Mesmer, Svengali, actor, bamboozler, befuddler,
   beguiler, charmer, counterfeiter, deceiver, deluder, dissembler,
   dissimulator, dodger, double-dealer, duper, enchanter, entrancer,
   faker, fooler, forger, gay deceiver, hoaxer, hypnotist, hypnotizer,
   jilt, jilter, joker, jokester, kidder, leg-puller, misleader,
   plagiarist, plagiarizer, playactor, practical joker, ragger,
   role-player, seducer, spoofer, tease, teaser