The Collaborative International Dictionary of English v.0.48:

Hoaxer \Hoax"er\, n.
   One who hoaxes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

hoaxer
    n 1: someone who plays practical jokes on others [syn:
         prankster, cut-up, trickster, tricker, hoaxer,
         practical joker]