Rainier III, Prince of Monaco
Karel Schwarzenberg is the eldest son of Prince Karel VI of Schwarzenberg of the junior line (Second Majorat of the House of Schwarzenberg), and Princess Antonie von Fürstenberg. He is the 1,322nd Knight of the Order of the Golden Fleece of Austria. He is first cousin of Princess Ira and Prince Egon von Fürstenberg and second cousin of Rainier III, Prince of Monaco. By tradition, he holds the style of Serene Highness ().