Radiicephalus is a genus of fishes in the monotypic family Radiicephalidae. It was formerly thought to be a monotypic genus, comprising the single species Radiicephalus elongatus, commonly known as tapertail, until the 2018 description of Radiicephalus kessinger. It is a marine fish found in the central and eastern Atlantic and eastern Pacific Ocean. This species grows to 76 cm (30 in) in total length.