Dayus

Dayus may refer to:
 * Dayus (leafhopper), a genus of insects in the family Cicadellidae
 * Dayus, a genus of polychaete worms in the family Histriobdellidae; synonym of Steineridrilus
 * Dayus, a genus of crustaceans in the family Gynodiastylidae; synonym of Jennidayus
 * Kathleen Dayus (1903–2003), an English author