What black artist was featured on the post stamp?

But it's a bit of a challenge to answer your question because I'm guessing some of us are not sure about: the country you could mean (U.S.? Turkey? Russia? Canada?), the time reference you may mean (the first black artist? 1920's? Currently? etc); and what you mean by artist.

If you are speaking of the U.S. AND if you are asking who the first Black person was to be featured on their postage stamp, then your answer is Booker T. Washington.

Romare Bearden, an African-American has his works featured on a recent set of 4 Forever Stamps.