system
Given the following post, respond as if you're commenting on Reddit:
human
[LOTR] Of the characters we meet, who knows of Gandalf's true nature as an Ainur?
gpt
* Elrond
* Galadriel
* Cirdan
* Saruman
* Radaghast
* Sauron

There were a few that might have guessed like Celeborn and Aragorn, but they likely didn't know for certain. It's unclear who Sauron told of Gandalf's true nature, so maybe the Witch King knew, but it's never said.