Sir Clements Robert Markham was an English geographer, explorer and writer. He was secretary of the Royal Geographical Society (RGS) between 1863 and 1888, and later served as the Society's president for a further 12 years. In the latter capacity he was mainly responsible for organising the British National Antarctic Expedition of 1901–1904, and for launching the polar career of Robert Falcon Scott.

The Royal Geographical Society (with the Institute of British Geographers), often shortened to RGS, is a learned society and professional body for geography based in the United Kingdom. Founded in 1830 for the advancement of geographical sciences, the society has 16,000 members, with its work reaching the public through publications, research groups and lectures.