To start: I have no problem with people wishing Jackson had cast Polynesian hobbits or imagining African-American and other black actors as Lord of the Rings characters (Idris Elba as Aragorn? *grabby-hands*). But I also think this is fans bringing something extra into the world. I think Tolkien was writing a mythology for north-west Europe, so it just wasn't reflecting cultures we modern, global citizens would identify as giving us people "of color." If there are e.g. proto-Africans or pro-Malaysians, Tolkien's not really writing baout those characters.
Now, there's obviously minorities within the contexts of certain cultures, but that seems different from what we mean by people of color in the "real" world. Thanks to imperialism and colonization and all that, there's a tragic history of pointing to European culture and saying this is what it means to be civilized, with various non-European people (and peoples) pushing back from that. Lothiriel and Morwen Steelsheen marrying into the Rohirric royalty, or Arwen and Eowyn making their way in Gondor, they're certainly in the minority relevant to the dominant culture, but I'm not sure there's this universal "this-culture-is-the-default" assumption and all the harm that comes from that at play. Faramir obviously thinks Rohirrim are men of the twilight; but the Rohirrim of Fengel's time were probably just as suspicious of their new king who had gone and married one of those hoity-toity, overly pampered women of the south.
I suppose you could make a case that (say) Haradrim or Easterlings or even orcs were meant to be characters of color, but that seems to come down more to authorial bias than deep-seated racism. And even when they had a different color skin, you don't have the same history of slavery and using those biological differences to justify these great sociological injustices. I mean, assume for the moment that Gondorians represent the pinnacle of western-European Anglo-Saxon-ish "civilized" people, and the men of Harad and the Easterlings and that sort are... less white? Like Southern/eastern European, Arabic, Egyptian, that kind of thing? Even if you accept that analogy, the people of Gondor may think the Southrons are less civilized, and they may be less white, but those two beliefs don't seem connected the way they are in our real world.
So I'm curious. Do you think there's such a thing as a character of color in Tolkien's world? And if so who are they?