The great-great-grandfather of current head of the House of Hohenzollern held what official title?
Georg Friedrich, Prince of Prussia Georg Friedrich Ferdinand, Prince of Prussia (German: "Georg Friedrich Ferdinand Prinz von Preußen"; born 10 June 1976), is the current head of the House of Hohenzollern, the former ruling dynasty of the German Empire and of the Kingdom of Prussia. He is the great-great-grandson and historic heir of Wilhelm II, the last German Emperor and King of Prussia, who was deposed and went into exile upon Germany's defeat in World War I in 1918.
Frederick IX, Count of Hohenzollern Friedrich IX, Count of Hohenzollern (d. between 1377 and 1379), nicknamed "Fredrick the Old" or "the Black Count", was a German nobleman. He was the ruling count of Hohenzollern from 1339 until his death.