Either one we’ve seen or one we haven’t! In the canon lore he disguises himself as the Lord of Gifts from Valinor and works with Celebrimbor to create the rings of power. Elrond, Gil-Galad and Galadriel don’t trust him but don’t realize who he really is. My money is on Halbrand, as he’s a good smith and able to persuade people to do as he wants but it’s probably a false lead and he’ll come in later.
I've seen good arguments why the Meteor Man might be Sauron. It doesn't fit a lot of things from the Tolkien lore, but it does fit some hints from the show.
That's because they're completely mixing up the history. They're already hinting at the destruction of Numenor, and they've introduced all the characters involved in that (except Sauron himself), all of which should happen 2000 years after the forging of the rings. And they're even hinting at the dwarfs digging too deep in Khazad-Dum (4000 years in the future).
They're clearly writing a completely new timeline, made up of parts of Tolkien's timeline.
One of my biggest pet peeves in made up fantasy worlds is the fact that their worlds are absolutely static for hundreds or thousands of years at a time. Nations rise and fall constantly! Maps shift! First the kingship is in Eridu, now it's in Bad-Tibira! Then Bad-Tibira fell and the kingship was taken to Larag!
(Of course, this makes the trope I'm complaining about Older Than Dirt, since the Sumerian King List claims their kings ruled for tens of thousands of years)
Originally Sauron was a Maia who was 'good and uncorrupted' with a passion for order. He sided with Morgoth because he thought if they could control the minds of Middle-Earth they'd be better off. As far as I know, in the lore, Sauron isn't evil in the way he's portrayed in the movies in that his goal is to improve everyones lives through efficiency and order (so it's not as simple as light v dark).
Sauron can shape-shift so in the second age he shows himself as a fair and beautiful man, but he's also portrayed as a werewolf and vampire in the books at different times!
Interesting. Didn’t he lose that power when made the final Ring of Power, and when he activated it, he threw all of his “life force” in it (cruelty, malignancy etc.)
Yes in order to make the One Ring more powerful than the other rings he had to put his own strength into it. However the elven rings weren't made by Sauron so he couldn't control those (eventually worn by Gandalf, Galadriel, and Elrond), and if I remember right the Dwarfs were too stubborn to be controlled (or something), so only the humans ended up being controlled anyway.