Source : Webster's Revised Unabridged Dictionary (1913)

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

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

Source : WordNet®

wrongdoer
     n : a person who transgresses moral or civil law [syn: {offender}]