Alcínoo (classical Greek: Άλκίνοος; Romaniz.: Alkínoos), in Greek mythology, was the king of the Phaeacians who took in Ulysses when his ship sank near Esqueria (perhaps present-day Corfu).
He had five sons and a daughter, named Nausicaa, who found Ulysses on the beach. Alcinoo and his wife Aretê were respected and loved by their subjects, hospitably welcoming foreigners and soothing the suffering of shipwrecked people. Upon hearing Ulysses' story, he gave him gifts and a ship to return to Ithaca.
The Argonauts and Medea, on their return from Colchis, passed through the court of Alcinoo, where they found Aietes' emissaries seeking Medea to return her to her father. Medea and the emissaries decided that Alcinoa would be the arbiter, and the king decided that she should be returned if she was still a virgin, otherwise she should stay with Jason.
In order to save her from the punishment that awaited her in Colchis, he hastily married her to Jason. The Colcos, fearful of returning, stayed in Eskeria, while the Argonauts continued on their journey.