Acteus (Greek Ακταιος) was the first king of Attica, according to Pausanias. He was autochthonous, father of Aglauros, and father-in-law of Cicrope, the second king of Athens.
Some ancient Greek analysts considered that Acteus did not exist, Attica having remained deserted from the time of Ogiges until Cicrope.
According to tradition he gave the region of Attica his name (Acteia) before it was changed to Cecropia by Cécrope, but later it was renamed Attica because of Attis, Cranau's daughter.
According to William Smith, Acteu had three daughters - Aglauros, Herse and Pandroso - but no sons, and was succeeded in power by Cicrope, Aglauros' husband, however the ancient texts only mention Aglauros as his daughter and Cicrope's wife; Aglauros, Herse and Pandroso are Cicrope's daughters with Aglauros.
According to Pausanias, a group of Athenian contemporaries of his claimed that the giant Porphyrios would have been king before Acteus.