Thomas R. Defler (born 26 November 1941; Denver, Colorado) is a North American primatologist who lives and works in Colombia. Defler earned his PhD from the University of Colorado at Denver in 1976 and then moved to Colombia. He worked in eastern Colombia in the Llanos until 1984. Defler then worked in the Amazonian Vaupés Department where he developed and lived in his research station, Estación Biológica Caparú until 1998. In 1998, he was obligated to flee from his research station by FARC guerrillas. He had run a primate rehabilitation center in Vaupes. He is the author of several papers about primates and of the books Primates de Colombia (2003), Primates of Colombia (2004) and Historia Natural de los Primates Colombianos (2010) . He edited a monograph on woolly monkeys as well.