The king snake eel (Ophichthus rex) is an eel in the family Ophichthidae (worm/snake eels). It was described by James Erwin Böhlke and John H. Caruso in 1980. It is a marine, tropical eel which is known from Florida to Texas, USA, in the northern Gulf of Mexico in the western Atlantic Ocean. It dwells at a depth range of , and inhabits offshore waters. Males can reach a maximum total length of ; the maximum recorded weight is . caught by Patrick Lemire on the Texsun II out of Galveston, Texas in 1997.
The King snake eel is often caught near oil platforms by anglers.