Two-Face.

Diz, not sure if this counts but there was a short-lived Get Smart comic book series from Dell in the '60s, so...

Agent 99

Thing 1 and Thing 2

Round 2 has ended
The score so far:

Calidore 2
Cei-U 2
codystarbuck 2
Confessor 1
DogHouse Reilly 2
driver1980 2
DubipR 2
EdoBosnar 2
Farrar 2
foxley 2
Hoosier X 2
icctrombone 1
james 2
jason 1
Jeddak 2
MRPS_Missives 2
MWGallaher 1
Ricky Jackson 2
riv86672 2
Roquefort Raider 2
shaxper 1
Slam_Bradley 2
supercat 2
tarkintino 1

RR: Of course, I accept the Ancient One, One is a number.
Doghouse Reilly: I was on the fence with Astra Furst (I mostly want the "Name One" part of the game to prevent somebody naming large and limiting others from participating, though that really isn't a problem here). As a non-native German speakeer, I'd read Furst with a different pronounciation. But Furst (meaning Ruler or King in German, similar to dutch Vorst (which means both Ruler and Frost, making King Frost ripe for puns)) has its origin in Latin and basically means First, so you're completely correct and I'll count it.

And I'll try to include this bit every time as well:
Answers I had expected but didn't see: Agent 13 (Sharon Carter), any of the Umbrella Academy, various Number Ones (Secret Empire comes to mind, but it's a common naming convention, see also XIII as was posted), various Zero's.

For full disclosure to know what game we're playing and how far you can push things: I was fully prepared to accept Pieface as an answer. Or somebody using a name including Roman Numerals within the name (Citizen V, Professor X etc.) And even would be willing to accept a cheeky mathematician amongst us to argue for e and i as irrational numbers, but you'd need to have been very eloquent to make your case. But people came up with enough characters with more normal numbers, so none of this was necessary.

Also just for fun, I had some ideas in the early stages of the game for questions that I have since rejected because it'd require knowledge of specific titles and I don't like to move the questions in that directory:
- Name a Defender who was not an Avenger (this one left a bit of leeway for people to use Flash Gordon or The Phantom or some other creative solution, but still felt too limiting).
- Name a non-mutant member of the X-Men (this was actually the first question I came up with, but it would have been even more limiting).

Anyway onwards:

Example: Chateau de Moulinsart also known as Marlinspike Hall, Kasteel Molensloot or Schloss Mühlenhof in various translations (and probably many more). Home of Captain Haddock.
Limits:
1a: The building must have a name (so not just Spider-Man's home)
1b: Th building must not exist in the real world (a replica made later after the comic came out does not count. It can be inspired by a real building, but most be sufficiently different to not be an exact copy with a different name.

Hall of Justice

-M

Titans Tower