I was thinking of this the other day, no-one says the 'Benedict Cumperpatch who is a white actor' why is that? why the need to highlight the fact that a person is a different race?
And also, what is the best way to refer to their race? We call whites 'caucasian' but how should we refer to non-whites? I don't like the terms Black, or coloured, I prefer African American - but what if they're not African and not American?
What I (&we I suppose) should really be doing is ignore their ethnicity and just call them by their nationality.