扬三世（波兰语：Jan III；1629年8月17日－1696年6月17日；又译约翰三世 ），全名扬三世·索别斯基（波兰语：Jan III Sobieski），从1674年开始同时担任波兰国王及立陶宛大公，直到1696年离世。扬三世在位的廿二年间，是联邦最稳定的时期，这尤其在波兰－瑞典战争完结及赫梅尔尼茨基起义之后，更为重要。索别斯基以一位优良的军事指挥家而知名，特别是他曾于1683年维也纳之战战胜意图侵略欧洲的鄂图曼帝国而广受波兰人民的敬爱，打开波兰中兴的一页；并成为了基督世界的大英雄，甚至被教皇美誉为「基督教的救星」。连其手下败将土耳其人都敬畏地称其为「利奇斯坦（波兰古称）雄狮」。

John III Sobieski (Polish:Jan III Sobieski, Lithuanian:Jonas Sobieskis; 17 August 1629 – 17 June 1696), from 1674 until his death King of Poland and Grand Duke of Lithuania, was one of the most notable monarchs of the Polish–Lithuanian Commonwealth.

Sobieski's military skill, demonstrated in wars against the Ottoman Empire, contributed to his prowess as King of Poland. Sobieski's 22-year reign marked a period of the Commonwealth's stabilization, much needed after the turmoil of the Deluge and the Khmelnytsky Uprising. Popular among his subjects, he was an able military commander, most famous for his victory over the Turks at the 1683 Battle of Vienna. After his victories over them, the Ottomans called him the "Lion of Lechistan"; and the Pope called him the savior of Christendom.