WordNet (r) 3.0 (2006):

bad person
    n 1: a person who does harm to others [ant: good person]

Moby Thesaurus II by Grady Ward, 1.0:

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