An honor killing (American English), honour killing (Commonwealth English), or shame killing is the murder of an individual, either an outsider or a member of a family, by someone seeking to protect what they see as the dignity and honor of themselves or their family. Honor killings are often connected to religion, caste, and other forms of hierarchical social stratification, or to sexuality. Most often, it involves the murder of a woman or girl by male family members, due to the perpetrators' belief that the victim has brought dishonor or shame upon the family name, reputation or prestige. Honor killings are believed to have originated from tribal customs. They are prevalent in various parts of the world, as well as in immigrant communities in countries which do not otherwise have societal norms that encourage honor killings. Honor killings are often associated with rural and tribal areas, but they occur in urban areas as well.

Although condemned by international conventions and human rights organizations, honor killings are often justified and encouraged by various communities. In cases where the victim is an outsider, not murdering this individual would, in some regions, cause family members to be accused of cowardice, a moral defect, and subsequently be morally stigmatized in their community. In cases when the victim is a family member, the murdering evolves from the perpetrators' perception that the victim has brought shame or dishonor upon the entire family, which could lead to social ostracization, by violating the moral norms of a community. Typical reasons include being in a relationship or having associations with social groups outside the family that may lead to social exclusion of a family (stigma-by-association). Examples are having premarital, extramarital or postmarital sex (in case of divorce or widowship), refusing to enter into an arranged marriage, seeking a divorce or separation, engaging in interfaith relations or relations with persons from a different caste, being the victim of a sexual crime, dressing in clothing, jewelry and accessories that are associated with sexual deviance, engaging in a relationship in spite of moral marriage impediments or bans, and homosexuality.

Though both men and women commit and are victims of honor killings, in many communities conformity to moral standards implies different behavior for men and women, including stricter standards for chastity for women. In many families, the honor motive is used by men as a pretext to restrict the rights of women. Honor killings are performed in communities with the intent to punish violations of social, sexual, religious or family norms or hierarchies. In many cases, the honor killings are committed by family members against a female relative considered to have disgraced her family.

Honor killings are primarily associated with Greater Middle East and South Asian countries such as India, Pakistan and Afghanistan, but are also rooted in other cultures, such as the Philippines.