Source : Webster's Revised Unabridged Dictionary (1913)

Vilifier \Vil"i*fi`er\, n.
   One who vilifies or defames.

Source : WordNet®

vilifier
     n : one who attacks the reputation of another by slander or
         libel [syn: {defamer}, {maligner}, {slanderer}, {libeler},
          {backbiter}, {traducer}]