Nycticeinops is a genus of vesper bat in the family Vespertilionidae. It contains the following species: Formerly, the only species placed in this genus was Schlieffen's serotine (N. schlieffeni), but phylogenetic evidence has placed several other species in this genus. These species were formerly classified in either Pipistrellus, Neoromicia, or Hypsugo until being reclassified into the new genus Parahypsugo in 2019. In a 2020 study, Nycticeinops was found to contain Parahypsugo, and thus both were synonymized.