John II, Duke of Schleswig-Holstein-Haderslev

John of Denmark or John the Elder was the only Duke of Schleswig-Holstein-Haderslev. The predicate the Elder is sometimes used to distinguish him from his nephew, John the Younger, who held Sønderborg from 1564 as a partitioned-off duke. As a co-ruler in the duchies of Holstein and of Schleswig, John the Elder is numbered as John II, continuing counting King John of Denmark as John I, Duke of Holstein and Schleswig.

21 June 1521

Born on the same birth day (21 June): Conrad Hall • Hussein El Shahat • Jim Douglas • John W. Dower • Luigi Tripepi • Min (South Korean singer) • Pablo Barrera • Pavel Haas • Pier Luigi Nervi • Sascha Konietzko • William Brede Kristensen

Born in the same month (June 1521): Maria of Portugal, Duchess of Viseu