Władysław IV Vasa, Polish king (d. 1648)
Władysław IV Vasa or Ladislaus IV of Poland (9 June 1595 – 20 May 1648) was King of Poland, Grand Duke of Lithuania and claimant of the thrones of Sweden and Russia, who ruled from 1632 until his death in 1648. Władysław IV was the eldest son of Sigismund III Vasa and his wife, Anna of Austria.

Born into the House of Vasa, Władysław was elected Tsar of Russia by the Seven Boyars in 1610 when the Polish army captured Moscow, but did not assume the throne due to his father's position and a popular uprising. Nevertheless, until 1634 he used the titular title of Grand Duke of Muscovy, a principality centered around Moscow. Elected king of Poland in 1632, he was largely successful in defending the Polish–Lithuanian Commonwealth against foreign invasion, most notably in the Smolensk War of 1632–34, in which he participated personally.

He supported religious tolerance and carried out military reforms, such as the founding of the Commonwealth Navy. Władysław was also a renowned patron of the arts and music. He failed, however, at reclaiming the Swedish throne, gaining fame by defeating the Ottoman Empire, strengthening royal power, and reforming the Commonwealth's political system. Despite these failures, his personal charisma and popularity among all segments of society contributed to relative internal calm in the Commonwealth.

He died without a legitimate son and was succeeded to the Polish throne by his half-brother, John II Casimir Vasa. Władysław's death marked the end of relative stability in the Polish–Lithuanian Commonwealth, as conflicts and tensions that had been growing over several decades came to a head with devastating consequences. The Khmelnytsky Uprising in the east (1648) and the subsequent Swedish invasion ("the Deluge", 1655–60) weakened the country and diminished Poland's status as a regional power. For this reason, Władysław's reign was seen in following decades as a bygone golden era of stability and prosperity.