Pieter Mauritz Retief (12 November 1780 – 6 February 1838) is a South African Boer leader.

Settling in 1814 in the frontier region of the Cape Colony, he assumes command of punitive expeditions in response to raiding parties from the adjacent Xhosa territory.

He becomes a spokesperson for the frontier farmers who voice their discontent, and writes the Voortrekkers' declaration at their departure from the colony.

He is a leading figure during their Great Trek, and at one stage their elected governor.

He proposes Natal as the final destination of their migration and selects a location for its future capital, later named Pietermaritzburg.

Following the massacre of Retief and his delegation by Zulu king Dingane, the short-lived Boer republic Natalia suffers from ineffective government and succumbs to British annexation.