We have no information at all about Galdor's birth or his age at the end of the Third Age, but his association with Círdan the Shipwright (one of the oldest Elves in Middle-earth) means that he might plausibly have been very old indeed. It is even conceivable that Galdor, like Círdan, had been part of the Great Journey, and had lived during the time before the making of the Sun and Moon.

Tolkien himself was uncertain on Galdor's roots, placing him alternately among those Sindar who had never left Middle-earth, or among those Noldor who returned from Aman and remained in Middle-earth after the end of the First Age.

The association of the name Galdor with a word for 'tree' is due to the name's history; in the earliest stories of Gondolin it belonged to the leader of the House of the Tree in Gondolin. Indeed, Tolkien pondered the possibility that this Elf of Gondolin might have been the same character we meet at Rivendell, and this is not completely impossible, but the Lost Tales explicitly describe him as crossing the Sea to dwell in Tol Eressëa.

Even in The Lord of the Rings, the name Galdor did not originally belong to the messenger of Círdan, but started out in the earliest drafts as that of a quite different Elf at the Council of Elrond. That Elf would eventually become known by the name of Legolas Greenleaf.