We know of two birds that were given the title 'Lord of Eagles': the mighty Thorondor in the First Age, and the chief Eagle encountered by Bilbo Baggins and his companions in the Misty Mountains long afterward in the Third Age. It is far from clear whether the title is applied to these birds in the same way, or whether there was any kind of succession in place. In other words, we can't be sure whether any later 'Lords of Eagles' held the same title as Thorondor in the First Age.

It also remains unclear whether Gwaihir the Windlord should be counted as a Lord of Eagles, or indeed whether he was the same Eagle encountered by Bilbo. Gwaihir is never strictly identified as any kind of lord or chief, though he is said to be the mightiest of the Eagles of that time, and a descendant of Thorondor. We might therefore reasonably extend the time of the Lord of Eagles at least to the end of the Third Age and on into the Fourth.