Cephisia or Kephisia (Ancient Greek: Κηφισιά) was a deme of ancient Attica, of the phyle of Erechtheis, sending six or eight delegates to the Athenian Boule. Strabo states that Cephisia was one of the twelve original cities of Attica founded by the mythical king of Athens Cecrops II and one of cities Theseus would later unite in the city-state of Athens.