Henri, Count of Paris and Head of the House of Orléans, died today. He was one of several people who might have been king of France if history had gone in a different direction. The Orléanist pretenders are the senior male-line descendants of King Louise Philippe, the last king of France (although he used the title "King of the French"). The descendants of Louise Philippe I also include the current king of the Belgians, the former tsars of Bulgaria, and the current heir to the imperial throne of Brazil.
Here's a family tree chart that explains it all. Click for a better view or to download (free):