杂种;坏蛋;混蛋 Bastard is an insulting word which some people use about a person, especially a man, who has behaved very badly.
(走运或倒霉的)家伙 Some people say things such as lucky bastard or poor bastard to refer to a person, usually a man, who they think is very lucky, or very unlucky.
N-COUNT 私生子(可能具冒犯意味) A bastard is a person whose parents were not married to each other at the time that he or she was born. This use could cause offence.