felon

criminal, crook, culprit, lawbreaker, malefactor, offender, perp, perpetrator, transgressor

baddie (or baddy), beast, brute, caitiff, devil, evildoer, fiend, heavy, hound, knave, meanie (also meany), miscreant, monster, nazi, no-good, rapscallion, rascal, reprobate, rogue, savage, scalawag (or scallywag), scamp, scapegrace, scoundrel, varlet, villain, wretch

villainess

sinner, trespasser, wrongdoer

cad, heel, serpent, snake, viper

bandit, bravo, desperado, outlaw

con, convict, jailbird

assassin, cutthroat, gangster, goon, gunman, hoodlum, hooligan, racketeer, ruffian, thug

rough, rowdy, tough

loser, lowlife, ne'er-do-well, stinker, trash