Synonyms for Hardhearted (same or very similar meaning)
WordNet sense 1 (showing unfeeling resistance to tender feelings):
obdurateWordNet sense 2 (lacking in feeling or pity or warmth):
heartlessWordNet sense 3 (devoid of feeling for others):
unfeeling, stonyheartedWordNet sense 4 (lacking compassion or feeling for others):
uncompassionateFrom the ODE community, based on WordNetadd/edit