J.R.R. Tolkien names Eärendil as the father of Elrond and Elros in The Silmarillion. Eärendil is a mariner whose voyage to the West becomes one of the central heroic stories of Tolkien’s First Age.
Eärendil is the son of Tuor, a Man, and Idril, an Elf of Gondolin. He marries Elwing, who is descended from both Elves and Men. Their sons, Elrond and Elros, therefore inherit a mixed lineage and later make different choices about their kindreds.
Eärendil sails to Valinor carrying a Silmaril and asks the Valar for aid against Morgoth. The Valar answer his plea, and Eärendil is set in the sky as a star. In The Lord of the Rings, the light associated with that star survives in Galadriel’s gift to Frodo.