Aventinus was a son of Hercules

Hercules

Hercules is the Roman name for Greek demigod Heracles, son of Zeus , and the mortal Alcmene...

 and the priestess Rhea mentioned 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...

, Book vii. 656, as an ally of Mezentius

Mezentius

In Roman mythology, Mezentius was an Etruscan king, and father of Lausus. Sent into exile because of his cruelty, he moved to Latium. He reveled in bloodshed and was overwhelmingly savage on the battlefield, but more significantly to a Roman audience he was a contemptor divum, a "despiser of the...

 and enemy of 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...

 (Dryden's translation):
Servius on this passage speaks of an Aventinus, a king of the aboriginal inhabitants of Rome, who was killed and buried on the hill afterwards called the Aventine Hill

Aventine Hill

The Aventine Hill is one of the seven hills on which ancient Rome was built. It belongs to Ripa, the twelfth rione, or ward, of Rome.-Location and boundaries:The Aventine hill is the southernmost of Rome's seven hills...

. This king may be conflated with the Aeneid figure or with Aventinus

Aventinus (king)

Aventinus, one of the mythical kings of Alba Longa, who was buried on the Aventine Hill later named after him. He is said to have reigned thirty-seven years, and to have been succeeded by Procas, the father of Amulius....

:

"The Aventine is a hill in the city of Rome. It is accepted that it derives its name from birds (aves) which, rising from the Tiber, nested there (as we read in the eighth book of a suitable home for the nests of ill-omened birds). This is because of a king of the Aboriginal Italians, Aventinus by name, who was both killed and buried there - just as the Alban king Aventinus was, he who was succeeded by Procas. Varro, however, states that amongst the Roman people, the Sabines accepted this mountain when it was offered them by Romulus, and called it the Aventine after the Aventus river in its area. It is therefore accepted that these different opinions came later, for in the beginning it was called Aventinus after either the birds or the Aboriginal King: from which it is accepted that the son of Hercules mentioned here took his name from that of the hill, not vice versa."http://www.perseus.tufts.edu/cgi-bin/ptext?doc=Perseus%3Atext%3A1999.02.0053&layout=&loc=7.657

This Aventinus (the son of Hercules) is not mentioned elsewhere in classical literature.