Great piece by Nnedi Okorafor about Steve Barne's Magic Negro archetype (I guess Steve didn't invent it, but I heard about it first from him, too) in the work of Stephen King. The Magic Negro is a self-sacrificing Person of Color (generally black, sometimes Amerind) who allows the (white) protagonist of the story to succeed - in movies, generally at the cost of their own life.
The Magic Negro is harmless because he is pure, and is pure because he is (as a primitive) in touch with his magical pre-technological self. I think he's a Person of Color because of the inherent magicalness of the Other - I mean seriously, Africa is drenched with story, so it's perfectly logical to imagine this Magic Negro archetype coming from Africa. And pre-Columbian America works just as well.
Isn't Sean Connery a Magical Negro in Highlander, really? He's Egyptian, sure - the point being he's foreign.
Steve's (and Okorafor's) position is that, in the context of American racial issues, the harmlessness of the Magic Negro makes him an acceptable character. He's almost always the only black in a cast of whites, and he dies safely. Steve can be quite cutting about it, in his own always-nice way. And he's so very right, too.
Anyway. The Magic Negro. Interesting stuff.