(s)barbarous, brutal, cruel, fell, roughshod, savage, vicious(of persons or their actions) able or disposed to inflict pain or suffering“a barbarous crime”, “brutal beatings”, “cruel tortures”, “Stalin's roughshod treatment of the kulaks”, “a savage slap”, “vicious kicks”
(s)heavy-handed, roughshodunjustly domineering“incensed at the government's heavy-handed economic policies”, “a manager who rode roughshod over all opposition”