Mnestheus is a character from Roman mythology

Roman mythology

Roman mythology is the body of traditional stories pertaining to ancient Rome's legendary origins and religious system, as represented in the literature and visual arts of the Romans...

, found in Virgil

Virgil

Publius Vergilius Maro, usually called Virgil or Vergil in English , was an ancient Roman poet of the Augustan period. He is known for three major works of Latin literature, the Eclogues , the Georgics, and the epic Aeneid...

's Aeneid

Aeneid

The Aeneid is a Latin epic poem, written by Virgil between 29 and 19 BC, that tells the legendary story of Aeneas, a Trojan who travelled to Italy, where he became the ancestor of the Romans. It is composed of roughly 10,000 lines in dactylic hexameter...

. He is described by Virgil as the ancestral hero of the Memmii and "Of the house of Assaracus". One of a handful of vaguely defined lieutenants under Aeneas

Aeneas

Aeneas , in Greco-Roman mythology, was a Trojan hero, the son of the prince Anchises and the goddess Aphrodite. His father was the second cousin of King Priam of Troy, making Aeneas Priam's second cousin, once removed. The journey of Aeneas from Troy , which led to the founding a hamlet south of...

, he appears to be Aeneas's most senior captain, taking charge in Book 9 in his absence. He takes second place in the boat race during the funeral games of Anchises

Anchises

In Greek mythology, Anchises was the son of Capys and Themiste . His major claim to fame in Greek mythology is that he was a mortal lover of the goddess Aphrodite . One version is that Aphrodite pretended to be a Phrygian princess and seduced him for nearly two weeks of lovemaking...

in Book 5.