Ferdinand Zvonimir von Habsburg (Ferdinand Zvonimir Maria Balthus Keith Michael Otto Antal Bahnam Leonhard; born 21 June 1997 in Salzburg), referred to in Austria as Ferdinand Zvonimir Habsburg-Lothringen, in Hungary as Habsburg Ferdinánd Zvonimir, and by his royal name as Archduke Ferdinand Zvonimir of Austria, is the eldest son of Karl von Habsburg, now head of the House of Habsburg-Lorraine.