Mr nice guy, as the name implies, refers to someone who is gentle, kind, and amiable. However, many people display opposite traits, depicting a big contrast from being nice. The antonyms for Mr nice guy include unkind, cruel, unfriendly, harsh, mean, ill-tempered, unpleasant, and rude. Being unkind entails showing no sympathy, care or consideration for others' feelings. Someone who is cruel derives pleasure in inflicting pain to others. The opposite of being friendly is unfriendly, meaning showing hostility or indifference to people. A harsh person is severe, uncompromising, and unrelenting. Being mean depicts a lack of kindness, having a bad temper or making derogatory remarks. Ill-tempered means being easily provoked, and unpleasant denotes causing discomfort, displeasure or distaste.