1. Octavia Butler
Definitely a favorite with me, Butler is the author of some of the best science fiction novels to come out of the era following the Golden Age, rivaling even the greats of the pre-social-revolution period. From Parable to the Sower to her Xenogenesis series, Butler has captivated readers everywhere with her brilliant examinations of the human condition. If you haven't read her work, you should, and I'd recommend her stuff to anyone who happens to like speculative fiction, even if science fiction isn't your thing; her work is sort of universal.
2. Tananarive Due
Author of one of my favorite short stories, "Like Daughter," Due has captured in so few words some of the most pressing issues of our time, from cloning to the lack of Black "heroes" in fiction. She even works with Blair Underwood, if you believe it, and that's pretty cool in my book. Fantastic writer and definitely worth reading.
3. Samuel R. Delany
One of the best literary critics and science fiction/fantasy writers of all time, Delany has a knack for philosophy, world building, and downright in-depth storytelling. His critical essays on science fiction are particularly interesting, in case you're into that stuff. If not, check out some of his best science fiction works such as Dhalgren or Babel-17.
4. George Schuyler
Author of Black No More, probably one of those novels you should read even if you're not a science fiction reader, Schuyler has had a rather strong career dealing with issues of color, humanity, and much more. Black No More is a poignant social commentary on the culture of "whitening" (or creation of products to de-black African Americans so they could fit in) that gained prominence during the early 1900s. Definitely worth picking up.
5. Nalo Hopkinson
Recognized as an author who draws upon her Caribbean roots, Nalo has had a brilliant career in the fantasy/cross genre world, writing such greats as Brown Girl in the Ring and working with Uppinder Mehan on the collection So Long Been Dreaming. I'd recommend her works if you like softer science fiction or crossover work, particularly Brown Girl in the Ring, which begs a lot of questions about organ donors in the future and the nature of culture and magic in a dystopic setting.
And there you have it. What do you think are some must-read black science fiction authors? Particularly I'm thinking of authors who might not be so clearly labeled as fantasy or science fiction, but the names are escaping me at the moment. Feel free to tell me in the comments! I know I'm missing some folks!