The Dark-shouldered snake eel (Ophichthus cephalozona, also known commonly as the Headsaddle snake eel, the Black-neck snake eel, the Blacksaddle snake eel, or the One-banded snake-eel) is an eel in the family Ophichthidae (worm/snake eels). It was described by Pieter Bleeker in 1864. It is a tropical, marine eel which is known from the Pacific Ocean, including the East Indies, the Society Islands, the Mariana Islands, Queensland, the Marshall Islands, Micronesia, Japan, and India. It dwells at a depth range of 2–15 metres, and inhabits reefs. It forms burrows in mud and sand, and forages during the night. Males can reach a maximum total length of 115 centimetres.