assassinator

from WordNet (r) 3.0 (2006)

assassinator
    n 1: a murderer (especially one who kills a prominent political
         figure) who kills by a surprise attack and often is hired
         to do the deed; "his assassins were hunted down like
         animals"; "assassinators of kings and emperors" [syn:
         {assassin}, {assassinator}, {bravo}]

from The Collaborative International Dictionary of English v.0.48

Assassinator \As*sas"si*na`tor\, n.
   An assassin.
   [1913 Webster]