The Collaborative International Dictionary of English v.0.48:

Wrongdoer \Wrong"do`er\, n.
   1. One who injures another, or who does wrong.
      [1913 Webster]

   2. (Law) One who commits a tort or trespass; a trespasser; a
      tort feasor. --Ayliffe.
      [1913 Webster]

WordNet (r) 3.0 (2006):

wrongdoer
    n 1: a person who transgresses moral or civil law [syn:
         wrongdoer, offender]

Moby Thesaurus II by Grady Ward, 1.0:

29 Moby Thesaurus words for "wrongdoer":
   bad person, criminal, crook, culprit, deceiver, delinquent,
   evil man, evil person, evildoer, felon, gangster, lawbreaker,
   malefactor, malevolent, malfeasant, malfeasor, misdemeanant,
   misdemeanist, misfeasor, mobster, offender, outlaw, public enemy,
   racketeer, sinner, thief, transgressor, villain, worker of ill



Bouvier's Law Dictionary, Revised 6th Ed (1856):

WRONG-DOER. One who commits an injury, a tort-feasor. (q.v.) Vide Dane's
Abridgment, Index, h.t.