Abyssomedon (meaning "Guardian of the Abyss") is an extinct genus of a nyctiphruretid parareptile known from the late Early Permian (Kungurian age) Garber Formation of Comanche County, Oklahoma, south-central United States. It contains a single species, Abyssomedon williamsi, which represents the third known nyctiphruretid species, the oldest species of the family and the first to be discovered in North America.