Abyssomedon (meaning "Guardian of the Abyss") is an extinct genus of a nyctiphruretid parareptile known from Early Permian (Artinskian age) fissure fills at Richards Spur in Comanche County, Oklahoma, south-central United States. It contains a single species, Abyssomedon williamsi, which represents oldest known nyctiphruretid species and the first to be discovered in North America.