Johann Theodor Kleinschmidt (6 March 1834 in Wolfhagen – 10 April 1881 in Utuan, Duke of York Islands, Bismarck Archipelago) was a German trader, explorer and naturalist. He sometimes anglicised his name as John Theodore Klinesmith. He worked for the J. C. Godeffroy and Sohn and collected natural history specimens for Museum Godeffroy as well as some European collectors. He was murdered on the island of Utuan in New Britain.