The Terran Trade Authority is a science-fiction setting originally presented in a collection of four large illustrated science fiction books published between 1978 and 1980. This series was written by Stewart Cowley.

The books formed a connected space-opera milieu, describing the future history of mankind's expansion into the galaxy, presented in the guise of official handbooks by the trade organization from which the setting takes its name. However, the books sometimes contained contradictory information (e.g., the nature of early FTL technology).

Compared to other science fiction settings, the TTA setting appears optimistic about man's place in the universe, though elements of violence and authoritarianism do appear in the books. It features a strong undercurrent of wonder and adventure, due in part to the inclusion of various mysterious alien relics and incidents that are left unexplained by the author.