Theodoor Hendrik van de Velde (12 February 1873, Leeuwarden – 27 April 1937 near Locarno in a plane crash) was a Dutch physician and gynaecologist who served as director at the Gynaecological Institute in Haarlem. His 1926 book Het volkomen huwelijk (The Perfect Marriage) made him an instant international celebrity. The English translation, Ideal Marriage: Its Physiology and Technique was the best-known work on its subject for several decades, and was reprinted 46 times in the original edition, selling well over a half-million copies.