The Territorial Imperative: A Personal Inquiry Into the Animal Origins of Property and Nations is a 1966 nonfiction book by American writer Robert Ardrey. It describes the evolutionarily determined instinct among humans toward territoriality and the implications of this territoriality in human meta-phenomena such as property ownership and nation building. The Territorial Imperative was an immediate success and remains a widely influential work of popular science. It extended Ardrey's groundbreaking anthropological work, contributed to the development of the science of ethology, and encouraged an increasing public interest in human origins.

Robert Ardrey was an American playwright, screenwriter and science writer perhaps best known for The Territorial Imperative (1966). After a Broadway and Hollywood career, he returned to his academic training in anthropology and the behavioral sciences in the 1950s.