Cleopatra VII would be one of these; she’s always depicted as being beautiful, but she was so inbred that she put Charles II of Spain to shame. Just look at this family treewreath:

Cleopatra’s coefficient of inbreeding was a fucking staggering 0.45, so almost half her alleles were probably identical. Charles II’s inbreeding coefficient was a paltry 0.25 and he looked like this, so I leave it to you to ponder how hot Cleopatra would have been exactly: