A bit like the last term I blogged, marica, negro is widely used somewhat affectionately in Colombia. Translating it as black man doesn't convey any affection. Blackie isn't quite right either, and sounds shocking in English, but to leave it in Spanish or not render it (two options I've seen) leaves the listener missing how constant naming by color is normalized.
Unlike marica however, which is widely used as a teasing but still charged term of endearment of sorts with people who are not actually gay, the term negro is primarily used for people with darker skin - though note that they often don't actually have African heritage. In Colombia often the darkest child in the family will be nicknamed el negro and the lightest el mono. In a translation you could leave the term as negro and add a footnote, but this term is more of a challenge when interpreting (which is oral, as opposed to translation, which is written).
How have other interps handled this one? Suggestions?