Archduke Franz Karl Joseph of Austria was a member of the House of Habsburg-Lorraine. He was the father of two emperors: Franz Joseph I of Austria and Maximilian I of Mexico. Through his third son Karl Ludwig, he was the grandfather of Archduke Franz Ferdinand of Austria – whose assassination sparked the hostilities that led to the outbreak of World War I – and the great-grandfather of the last Habsburg emperor Karl I.

The House of Habsburg-Lorraine originated from the marriage in 1736 of Francis III, Duke of Lorraine and Bar, and Maria Theresa of Austria, later successively Queen of Bohemia, Queen of Hungary, Queen of Croatia and Archduchess of Austria. Its members are the legitimate surviving line of both the House of Habsburg and the House of Lorraine and inherit their patrimonial possessions from their female line of the House of Habsburg and from the male line of the House of Lorraine.