Another word for ruthless
Without pity; said of persons
pitiless, unpitying, merciless, unmerciful, tigerish, feral, ferine, ferocious, stony-hearted, heartless, obdurate, cold-blooded, remorseless, vindictive, vengeful, revengeful, rancorous, implacable, unforgiving, malevolent, hardhearted, hard, cold, unsympathetic, unforbearing, vicious, sadistic; see also sense 2; cruel 2.
Showing little evidence of pity; said of actions, policies, etc.
savage, brutal, cruel, tyrannical, relentless, barbarous, inhuman, callous, grim, atrocious, flagrant, terrible, abominable, outrageous, inexorable, unrelenting, fiendish, oppressive, bloodthirsty, venomous, galling, dog-eat-dog; see also cruel 1.