Nycticeius is a small genus of bats in the vesper bat family, Vespertilionidae, and the only member of the tribe Nycticeiini. It contains three species, the evening bat, the Cuban evening bat and Nycticeius aenobarbus. Some authorities include several other Old World species in Nycticeius, but recent genetic work shows that is a completely New World genus. Nycticeius is of Greek and Latin origin, meaning "belonging to the night".