Princess Charlotte

Born to King George IV and Caroline of Brunswick, she was the only legitimate heir to the throne. She married Leopold in 1816 and was soon pregnant with a child. She died a few days later after delivering a stillborn son due to complications. Leopold was said to be very heartbroken by her death. Had she not died, she would have been the Queen of the United Kingdom and Leopold would have been named Prince Consort. Those positions were later given to Queen Victoria and Albert respectively.