In Sandman #73 by Neil Gaiman, the character Hob Gadling (who is meant to have been alive for hundreds of years) was having a discussion with his girlfriend, who said that there were no black queens of England. He retorts that Catherine of Aragon was black, and provides the following explanation:
There were a lot of Moors and Africans in Spain and Italy in the old days. Remember Othello? Trust me, if Catherine of Aragon had been in Alabama in the 1950's, they'd have made her ride in the back of the bus.
How accurate is this statement? According to Wikipedia, this is a portrait of her, and she does not appear to be black to me.
No, she was not. I like what Gaiman was doing with the scene (challenging the reader's perceptions, reminding the reader that Hob's immortal), but it's not really based on anything. Catherine of Aragon's ancestry is well-documented, and medieval/early modern European royalty, as I've written before, was essentially its own genetic pool. Portraits of her, her parents, and a number of her ancestors exist that show people who would have been considered white in 1950s Alabama.
I have a shortish previous answer on this, as well as this one about some of Catherine's ancestors.