Similar word to villainous:

atrocious, bad, corrupt, crooked, cruel, culpable, deplorable, depraved, diabolical, dirty, evil, felonious, hateful, ignoble, illegal, illicit, immoral, iniquitous, knavish, lawless, low, mean, nefarious, peccant, reprehensible, scandalous, shady, sinful, unlawful, vile, wicked