The Collaborative International Dictionary of English v.0.48:

Dissimulator \Dis*sim"u*la`tor\, n. [L.]
   One who dissimulates; a dissembler.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dissimulator
    n 1: a person who professes beliefs and opinions that he or she
         does not hold in order to conceal his or her real feelings
         or motives [syn: hypocrite, dissembler, dissimulator,
         phony, phoney, pretender]