The Collaborative International Dictionary of English v.0.48:

Celebrator \Cel"e*bra`tor\, n. [L.]
   One who celebrates; a praiser. --Boyle.
   [1913 Webster]

WordNet (r) 3.0 (2006):

celebrator
    n 1: a person who is celebrating [syn: celebrant,
         celebrator, celebrater]