The Collaborative International Dictionary of English v.0.48:
Sympathizer \Sym"pa*thi`zer\, n. One who sympathizes. [1913 Webster]WordNet (r) 3.0 (2006):
sympathizer n 1: commiserates with someone who has had misfortune [syn: sympathizer, sympathiser, comforter] 2: someone who shares your feelings or opinions and hopes that you will be successful [syn: sympathizer, sympathiser, well-wisher]