齐格蒙特·奥古斯特（波兰语：Zygmunt II August，鲁塞尼亚语：Żygimont III Awgust I，白俄罗斯语：Жыгімонт Аўгуст；立陶宛语：Žygimantas III Augustas I，德语：Sigismund II. August；1520年8月1日-1572年7月7日），波兰国王与立陶宛大公，齐格蒙特一世和王后博娜·斯福尔扎独子，在1548年继承王位。齐格蒙特·奥古斯特三次成婚，但膝下仍无子女，令雅盖隆王朝男嗣断绝，使卢布林联合引入选举君主制。

Sigismund II Augustus (Polish:Zygmunt II August, Ruthenian: Żygimont III Awgust I, Lithuanian:Žygimantas III Augustas I, German:Sigismund II. August) (1 August 1520 – 7 July 1572) was King of Poland and Grand Duke of Lithuania, the only son of Sigismund I the Old, whom Sigismund II succeeded in 1548. Married three times, the last of the Jagiellons remained childless, and through the Union of Lublin introduced an elective monarchy.