Dipsas oneilli, also known commonly as O'Neill's tree snake, is a species of snake in the subfamily Dipsadinae of the family Colubridae. The species is endemic to Peru.
The specific name, oneilli, is in honor of American ornithologist .
Dipsas oneilli is found in the Andes of northwestern Peru, on both the Pacific slope and the Amazonian slope, at elevations of .
Dipsas oneilli is arboreal.
Dipsas oneilli preys predominately upon mollusks.
Dipsas oneilli is oviparous.