Brettus is a genus of jumping spiders. Its six described species are found in southern Asia from India to China and Sulawesi, with a single species endemic to Madagascar. Two species in this genus, B. celebensis and B. madagascarensis, were originally described as members of the genus Macopaeus. According to Thorell, the genus name is taken from Greek mythology. Brettos (Βρεττος) was a son of Heracles (appears at Stephanus of Byzantium).