Władysław IV Vasa (Polish: Władysław IV Waza; Latin: Vladislaus IV Vasa or Ladislaus IV Vasa; Lithuanian: Vladislovas Vaza; 9 June 1595 – 20 May 1648) was a Polish prince from the Royal House of Vasa. He reigned as King of Poland and Grand Duke of Lithuania from 8 November 1632 to his death in 1648.

Władysław IV was the son of Sigismund III Vasa (Polish: Zygmunt III Waza) and his wife, Anna of Austria (also known as Anna of Habsburg). In 1610 the teen-aged Władysław was elected Tsar of Russia by the Seven Boyars, but did not assume the Russian throne due to his father's opposition and a popular uprising in Russia. Nevertheless, until 1634 he used the title of Grand Duke of Muscovy.

Elected king of Poland in 1632, Władysław was fairly successful in defending the Polish–Lithuanian Commonwealth against 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. He was also a renowned patron of the arts and music. He failed, however, to realize his dreams of regaining the Swedish crown, gaining fame by conquering the Ottoman Empire, strengthening royal power, and reforming the Commonwealth.

He died without a legitimate male heir and was succeeded to the Polish throne by his half-brother, John II Casimir Vasa (Jan Kazimierz Waza). 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, notably the largest of the Cossack uprisings – the Khmelnytsky Uprising (1648) — and the Swedish invasion ("the Deluge", 1655–60).