League of Nations mandates were the prototype of, and similar to, United Nations Trust Territories, authorising major powers (originally the victors in World War I) to administer former German and Turkish territories subject to regular reporting as to the wellbeing of the populations concerned to the League of Nations, the predecessor to the United Nations. Upon the entry into force of the Charter of the United Nations in late 1945, all the League of Nations mandates were to become United Nations Trust Territories.

The two most famous and controversial League of Nations mandates were the British mandate in Palestine, referred back to the UN in 1947 and abandoned the following May in the face of mounting local conflict arising from the demands of both Jews and Arabs for a national state (see British Mandate of Palestine); and the South African mandate in South-West Africa, or Namibia as it is now called, which the Pretoria government refused to convert to a United Nations Trusteeship from the League's eclipse until the territory's independence in March 1990.