a mythical king of the Tyrrhenians or Etruscans, at Caere or Agylla, and father of Lausus. When he was expelled by his subjects on account of his cruelty he took refuge with Turnus, king of the Rutulians, and assisted him in his war against Aeneas and the Trojans.
Aeneas wounded him, but Mezentius escaped under the protection of his son. When, however, Lausus had fallen, Mezentius returned to the battle on horseback, and was slain by Aeneas (The Aeneid Book VIII).
The story about the alliance between Mezentius and the Rutulians is also mentioned by Livy and Dionysius, but they say nothing about his expulsion from Caere or Agylla. According to them Aeneas disappeared during the battle against the Rutulians and Etruscans at Lanuviuni, and Ascanius was besieged by Mezentius and Lausus. In a sally at night the besieged defeated the enemy, slew Lausus, and then concluded a peace with Mezentius, who henceforth remained their ally. According to Servius Mezentius was slain by Ascanius.
During the siege of Ascanius, Mezentius, when he was asked to
conclude a peace, demanded among other things, that the Latins
should give up to him every year the whole produce of their
vintage and in commemoration of this, it was said, the Romans in
later times celebrated the festival of the Vinalia, on the
twenty-third of April, when the new wine was tasted, and a
libation made in front of the temple of Venus, and a sacrifice
offered to Jupiter.