[Legate of Amon Lanc]

I like your list - and this topic (and welcome to the 'Downs!). I would agree on most you have said, and mentioned on the list.

All the "obvious ones" are names which have the sound of "wow, what a powerful/ancient and wise/descended from incredibly legendary lineage/any other similarly good reasons guy". So, I think Gandalf, Aragorn, and Elrond for example are completely undebatable. Galadriel likewise (Sauron actually was supposed to really fear her) and even Celeborn, I think (even though did not seem so, hmm, how to say it, active at times, or as impressive, but still I think Sauron would not care and throw him in the same bag with Galadriel). Círdan would fit, too, if he was in that army, of course, as much as Saruman would.

I don't know about Radagast. Depends how much Sauron knew about him. If very little, he could fear him based on what he was (as in: "What is this? Another Gandalf? Perhaps weaker, but still similar in power? Then I should be afraid"). But I think from what Sauron was like, his reaction would be more similar to Saruman's: he would just laugh at Radagast. Though maybe if Radagast was a part of this large group of Aragorns, Gandalfs and others, it would add to his fears more than if there was, say, even a strong Gondorian general in there.

Speaking of that, Boromir would certainly qualify, had he been alive (he was a man with the reputation of a true warrior, and brave and all). Not sure if his brother had such a strong reputation as well, but maybe he would qualify as well. Which naturally leads me to concluding Imrahil might have qualified, if you count his blood too. We don't know what were his deeds otherwise - that is the only reason why I would doubt it. But if e.g. Imrahil used to be a feared foe of the Haradrim, then for sure. For that matter, your namesake seems to have enjoyed a rather good reputation, so even he might have been among those names (were he alive), if he was really e.g. a war hero or somesuch.

The Elves, however, probably mostly lack the fact of being known to Sauron for him to fear them. Glorfindel is one I am not sure about in this respect. I am sure that if Sauron knew about them, he would be freaked out maybe even more than about many of the others. (Well, maybe at least after the Fords of Bruinen he knew that there was something like that, from the Nazgul.) Elladan and Elrohir would be feared, for sure, just because of being Elrond's sons if nothing else, but also they seem to be well-known and also they are Orc-slayers and after joining Aragorn etc. they would be even more, so...

Eagles are something Sauron would deeply hate and yes, probably even fear on purpose (because of all the ancient stuff related to Thorondor being such a menace even for Morgoth etc.), but they won't probably count as "names" (I doubt Sauron knew the names of any Third Age eagles). That'd be the same with e.g. Ents (which he probably thought they didn't exist anymore just as much as Saruman did).

If we are speaking theoretically, people like Brand (from the lineage of the guy who had killed the dragon, if nothing else) or Dáin (a very famous Dwarf) would probably also fit. Maybe even Balin (again, had he lived).

(edit: cross-posted with Inzil)