The Collaborative International Dictionary of English v.0.48:

Tantalizer \Tan"ta*li`zer\, n.
   One who tantalizes.
   [1913 Webster]

WordNet (r) 3.0 (2006):

tantalizer
    n 1: someone who tantalizes; a tormentor who offers something
         desirable but keeps it just out of reach [syn:
         tantalizer, tantaliser]