An Italian hero who gave his name to the Faliscians of Falerii (a city which he founded in Etruria, and in which a dialect very closely related to Latin was spoken). The mythographers linked Halesus with Agamemnon, making him out to be the latter's companion, or even his illegitimate son, who had come to Italy to the time of the Trojan War. Other traditions portrayed him as a son of Neptune; and as such he was respected by Morrius, king of Veii, who initiated the carmen Saliare in his honour (this was the archaic song chanted by the Silians during certain ceremonies in Rome).

As a descendant of Agamemnon and a native of Argos, Halesus was numbered among the enemies of Aeneas when the latter landed in Italy. Halesus fought alongside Turnus, and was slain by Pallas.