I know you're probably thinking that Superman and Supergirl clearly weren't Black... BUT, DC Comics came up with a clever way to get around silly technicalities like plot continuity - The DC Multiverse. Basically, there are an infinite number of EARTHS and each has its own stories, heroes, history, etc. So in Multiverse Earth-D Superman and Supergirl are an African-American married couple and members of a multicultural Justice Alliance of America.... yup, you read that right.