It's harder for it to happen these days, but have you ever assumed that a famous person was one colour and found out, years later, that they were another colour? If so, who?
Throughout my teens I believed that Tim Westwood was black and was only put right on this in my twenties.

You're going to think I am making this up, but I know someone who thought the young Michael Jackson of "The Jacksons" fame was a different Michael Jackson from the middle-aged Michael Jackson of extensive plastic surgery fame.

To be fair, there are precious few people who were alive at the time who weren't fooled by the original sound of Boney M, who turned out not to be three black American women and a black American man, but one ginger German.