Ralph Alger Bagnold, OBE, FRS, (3 April 1896 – 28 May 1990) was an English 20th Century desert explorer, geologist and soldier.
In 1932 he staged the first recorded East-to-West crossing of the Libyan Desert.
His work in the field of Aeolian processes produced the book 'The Physics of Blown Sand and Desert Dunes', which has been used by United States' space agency "NASA" in its study of the terrain of the planet Mars, the "Bagnold Dunes" on Mars' surface being named after him by the organization.During World War 2 he was a soldier in the British Army, in which he founded the behind-the-lines reconnaissance, espionage and raiding unit the "Long Range Desert Group", serving as its first commanding officer in the North Africa Campaign.