The Culture series, by Iain M. BanksRead about the other entries on the list.
Banks’ classic series not only explicitly features a humanoid race that is fully racially integrated to begin with, it also gives its members near-total power over their bodies—sex, gender, and appearance—making every single physical attribute simply a matter of preference. This naturally renders any prejudice or distinctions based on those traits more or less meaningless, making the Culture perhaps the ultimate example of a colorblind civilization—at least when it comes to the humanoid characters. The artificial intelligences have their own prejudices to contend with.
Iain M. Banks' Culture novels appear on Annalee Newitz's top ten list of books we should read to understand brains of the future and Charlie Jane Anders's list of ten book series so addictive, you never want them to end. Consider Phlebas, the first story in the Culture series, is one of Peter Millar's six favorite satires on despotism.
--Marshal Zeringue