Trimeresurus sumatranus is a species of venomous pitviper (a subfamily of vipers within the larger Viperidae family) found in the tropical forests of Indonesia, Malaysia and Thailand.

Arboreal by nature, its coloration is pale to neon-green, with some black vertical markings, and a red-tipped tail.

Adults may attain 1.6 metres (5 feet 3 inches) SVL (snout–vent length), with fangs over 10 mm (3⁄8 in) long.

[5] The dorsal scales are edged with black, which may form crossbands in more mature specimens.

[7] Found in southern Thailand, West and East Malaysia (Sabah and Sarawak on Borneo) and Indonesia (Bangka, Billiton, Borneo, Sumatra and the nearby islands of Simalur, Nias, and possibly the Mentawai Islands [Sipora]).