desperado

bandit, bravo, outlaw

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

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

sinner, trespasser, wrongdoer

cad, heel, serpent, snake, viper

con, convict, jailbird

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

rough, rowdy, tough

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