I understand pretty much every RPG out there is, in fact, fantasy, and that the question I am asking may be somewhat laughable. But perhaps I missed something, perhaps one may exist.

An open-world RPG, but either historical or realistic, without any fantasy whatsoever. Medieval, or Roman-era, Feudal Japan, something of that nature. It'd be cool to find one set in Rome, and you can be a Roman soldier, or join one of their enemies, etc, but I am 100% sure that does not exist.

I just don't like all that "Behold my great power! I am the evil darkness that shall envelop this land! [Evil Laugh]" I don't like all the Necromancer, raise undead, fireball, ice, lightning, magical auras and whatnot.... to me it's just... I just don't like it. Dragons especially... all that "Oh, behold the Dragonborn" stuff just kind of puts me off. All that "The revered Dragonslayer! Who can consume the soul of a dragon!"... just... it's just not me.

Think of Skyrim, but without the fantasy elements. The Companions without werewolves, the Thieves without gods and goddesses, NO College, and the Dark Brotherhood without any fantasy in it. No elves, no dragons, no trolls, no giants, no giant spiders. No Daedra, no elven armor, no orcish armor, no mages, no enchanting, none of that.

Just good old fashioned iron, steel, leather, hide, fur... only Nords and Imperial... only bandits, sabrecats, deer, foxes, and rabbits... that's what I'd want.

Mount & Blade?

Fallout 3

Great question, I look for games like that as well.

Modern-setting sandboxes, outside of GTA styles, or non fantasy rpg setting, are not very common.