Eagle of the Crissaegrim, also called the Lord of Eagles and the King of Eagles. His name meant 'king eagle'. Thorondor was the first King of the Eagles during the First Age of the Sun. With a wingspan measured at thirty fathoms, he appears to have been the largest Eagle ever to have lived.

During the Wars of Beleriand, Thorondor rescued Maedhros from Thangorodrim, brought back the body of King Fingolfin from Angband, and scarred the face of Morgoth with his talons. Beren and Lúthien were also rescued from Angband by the Eagle Lord.

For centuries, Thorondor's eagles guarded the hidden realm of Gondolin from its enemies. However, Thorondor and his Eagles won great fame in the Great Battle by destoying the Winged Dragons of Angband.

Thorondor appears to have returned with the Valar to the Undying Lands at the end of the First Age.