When ever you hear about another PC on the forums or in the games, how does that character look in your mind ?

Arena: Male Altmer Battlemage
Daggerfall: Male Breton Nightblood
Battlespire: Male Altmer Battlemage
Morrowind: Female Dunmer Mage
Oblivion: Male Imperial Knight

Faceless. The opposite end of the pole is > insert any player's toon <. My feeling toward any PC for Elder Scroll series, really (minus Cyrus, of course).

I always imagine them as nothing. Barely there.

Something like that, basically, when I think of the protagonist of any Elder Scrolls game with character customization as a faceless entity, ready to be given whatever identity the player chooses. Or, if I'm playing the game, I tend to think of whatever character I'm currently using. In short, the Nerevarine, Champion of Cyrodiil, and so on, are not so much people as titles for roles that players can insert whatever character they create into.

For Oblivion the imperial knight was so advertised that it feels like the default one. For other games I haven't seen such advertising, which isn't surprising.

There's that Dunmer at the top of this page. The Nerevarine always seems like a Dunmer in my mind, like the one present on the game case and the top of this screen, right next to the Imperial.

ARENA: I played as a Nord burglar, but that doesn't really seem right, so...faceless.
Daggerfall: Altmer Spellsword
Battlespire: I didn't play it, but I always picture him as an Imperial. I don't even know if they existed at that point though.
Morrowind: The Neravarine is an Orc Knight named Gurbag gro-Bakka, well, mine was anyway.
Oblivion: The Champion of Cyrodill is definately an Imperial Knight.

Alternatively, the Neravarine could be Banden Indaris, the Redoran noble, but Gurbag was the first character that I defeated Dagoth Ur with, so I like to go with him.

For Morrowind for me would be a male, bald headed, ear ringed Dunmer adventurer. For Oblivion, would be an male Imperial adventurer.