The Collaborative International Dictionary of English v.0.48:

Offender \Of*fend"er\, n.
   One who offends; one who violates any law, divine or human; a
   wrongdoer.
   [1913 Webster]

         I and my son Solomon shall be counted offenders. --1
                                                  Kings i. 21.
   [1913 Webster]

WordNet (r) 3.0 (2006):

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

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "offender":
   criminal, crook, culprit, delinquent, evil man, evil person,
   evildoer, felon, lawbreaker, malefactor, malfeasor, miscreant,
   misdemeanant, misdemeanist, misfeasor, outlaw, sinner,
   transgressor, wrongdoer