Eru-begotten

The Eru-begotten, otherwise known as the First Elves or Unbegotten, were the very first 144 Elves who were awakened by Ilúvatar on the shores of Cuiviénen during the First Age. Each of them slept beside his or her spouse, and there were 72 such pairs.

It should be noted the name Firstborn did not apply as a demonym to the Eru-begotten only, but to all Elves as a whole instead.

The children of the Eru-begotten were known as the First-begotten, the "First Generation".