Colonel Charles Henry Dudley Ryder, (28 June 1868 - 13 July 1945) was an English army officer and explorer. An officer of the Royal Engineers, British Army, he served as Surveyor General of India from 1919 to 1924. During his career, he undertook a number of surveys; including in China's Yunnan province, Tibet and the Himalayas, the North-West Frontier Province, the Turco-Persian border, in Mesopotamia, and throughout India.