Knud Valdemar Gylding Holmboe (April 22, 1902 Horsens Denmark - October 13, 1931 Aqaba, Jordan) was a Danish journalist, author and explorer who converted from Protestantism to Catholicism in 1921, and, after a sojourn in North Africa, ultimately converted to Islam in 1929. Six years later, he published a book of his experiences on a journey through Libya, that later became famous. The book exposed the maltreatment of the population the author had witnessed on his journey and the atrocities committed by the Italian colonial power. Holmboe was murdered on his way to Makkah in Aqaba in October 1931.
Knud Holmboe is the elder brother of Danish composer Vagn Holmboe.