Sigismund I may refer to:
Sigismund of Burgundy (died 524), King of the Burgundians Sigismund I, Prince of Anhalt-Dessau (died 1405) Sigismund, Holy Roman Emperor (1368–1437) Sigismund I of Lithuania (c. 1365 – 1440) Sigismund, Archduke of Austria (1427–1496) Sigismund of Bavaria (1439–1501), Duke of Bavaria Sigismund I the Old (1467–1548), King of Poland and Grand Duke of Lithuania
See also Sigismund III Vasa (1566–1632), the first (and currently only) Sigismund to have reigned over Sweden Sigismund (disambiguation)