In Greek mythology, Arethusa (/ˌærɪˈθjuːzə/; Ancient Greek: Ἀρέθουσα) may refer to the following personages:

• Arethusa, one of the 50 Nereids, sea-nymph daughters of the 'Old Man of the Sea' Nereus and the Oceanid Doris.^[1] She was counted in the train of Cyrene along with her sister Opis, Deiopea and Ephyra.^[2]
• Arethusa, a nymph of a spring who was pursued by the river god Alpheus. She was a huntress and attendant of Artemis.^[3] She may be the same with the above Arethusa.
• Arethusa, one of the Hesperides according to Apollodorus.^[4][5][6][7]
• Arethusa, the Boeotian daughter of Hyperes,^[8] son of Poseidon and the Pleiad Alcyone. She was the mother of Abas, king of the Abantians in Euboea by Poseidon.^[9] The god had an intercourse with Arethusa in Boeotian Euripus and was changed into a fountain in Chalcis by Hera.^[8]
• Arethusa, a Euboean princess as daughter of King Abas and thus, granddaughter of the above Arethusa. She was the sister of Alcon, Dias^[10] and probably, of Canethus^[11] and Chalcodon.^[12]
• Arethusa, a Cretan woman, whose son was killed in the Trojan War. She was married to Thersander and their son was Hyllus.^[13]
• Arethusa, one of Actaeon's dogs.^[14]