According to one historian, Queen Victoria's grandmother Charlotte had African ancestry.
If you google Queen Charlotte of Mecklenburg-Strelitz, you'll quickly come across a historian called Mario de Valdes y Cocom. He argues that her features, as seen in royal portraits, were conspicuously African, and contends that they were noted by numerous contemporaries. He claims that the queen, though German, was directly descended from a black branch of the Portuguese royal family, related to Margarita de Castro e Souza, a 15th-century Portuguese noblewoman nine generations removed, whose ancestry she traces from the 13th-century ruler Alfonso III and his lover Madragana, whom Valdes takes to have been a Moor and thus a black African. [Link]