barbarous
adjective
1 the medieval ruler's barbarous reign formed the basis of the legend of Dracula:
cruel, brutal, barbaric, brutish, bestial, savage, vicious, fierce, ferocious, wicked, nasty, ruthless, remorseless, merciless, villainous, murderous, heinous, nefarious, monstrous, base, low, lowdown, vile, inhuman, infernal, dark, fiendish, hellish, diabolical, ghastly, horrible.
▷antonyms benevolent.