Bothrops barnetti, also known commonly as Barnett's lancehead and Barnett's pit viper, is a species of venomous snake, a pit viper in the subfamily Crotalinae of the family Viperidae.

[2] The specific name, barnetti, is in honor of Burgess Barnett (1888–1944), who collected the holotype and paratypes.

Dr. Barnett was Curator of Reptiles at the London Zoo (1932–1937) and Superintendent of the Rangoon Zoological Gardens (1938–1944).

Males usually grow to 120 cm (47 inches) in total length (including tail), whereas females are quite smaller and thinner.

The type locality given is "from the mouths of Quebradas Honda and Perines, between Lobitos and Talara, northern Peru".