“Out of the Great Sea to Middle-earth I am come.
In this place I will abide, through my heirs, unto the ending of the world.”
Elendil, in Quenya: “Elf-friend” was a Man of Númenor, the father of Isildur and Anárion, who led the survivors of its Downfall to the shores of Middle-earth where they founded two Realms in Exile, Arnor and Gondor.
Elendil became the first King of both realms holding the title of High King of the Dúnedain, making him supreme overlord of all exiled Númenóreans in the lands east of the Great Sea. Elendil established strong regimes there and created the great alliance that put an end to Sauron's power for over a thousand years.
His bloodline and spirited leadership survived in the Dúnedain of the North and South of Middle-earth, that would in turn sire the brave and heroic Men that would help bring a final end to Sauron in the War of the Ring.