The Collaborative International Dictionary of English v.0.48:
Vilifier \Vil"i*fi`er\ (v[i^]l"[i^]*f[imac]`[~e]r), n. One who vilifies or defames. [1913 Webster]WordNet (r) 3.0 (2006):
vilifier n 1: one who attacks the reputation of another by slander or libel [syn: defamer, maligner, slanderer, vilifier, libeler, backbiter, traducer]