Ian K. T. Sayer (born 30 October 1945) is a British entrepreneur, World War II historian, author and investigative journalist. His (established in 1967 and sold in 1979) became part of the British and European overnight door to door express parcels delivery industry. He currently acts as curator to the "Ian Sayer Archive", a collection of contemporary World War II documentation, which assists in providing information to institutions, other historians, authors and researchers of the period.