Sydney Dawson Bailey (1 or 2 September 1916 – 26 November 1995) was an English author, pacifist, and expert on international affairs. He worked at and was head of the Quaker United Nations Office during the 1950s. He was a conscientious objector during World War II, spending several years in the Friends' Ambulance Unit. Bailey wrote 17 books and worked at the Carnegie Endowment for International Peace from 1958 to 1960 as a visiting scholar. He then left the endowment and was involved in various negotiations and advisory councils before his death in 1995.