Lieutenant-General Pierre Derksen Steyn (born 25 November 1942) is a retired South African Air Force officer who served as Secretary for Defence from 1994 to 1998, and as Chief of Defence Force Staff from 1990 to 1993. He is also known as the chair of the Steyn Commission, which from 1992 to 1993 investigated allegations of criminal and third force activity by the apartheid-era South African Defence Force.