Augustus I may refer to: Augustus, Elector of Saxony (1526–1586) Augustus I, Duke of Brunswick-Lüneburg (1568–1636) Augustus, Grand Duke of Oldenburg (1783–1853) Sigismund II Augustus (1520–1572), King "Augustus I" of Poland and Grand Duke of Lithuania (c. 1766 – c. 1835), French engraver See also Frederick Augustus (disambiguation) Ernest August