Bronisław Maria Komorowski (Polish: [brɔˈɲiswaf kɔmɔˈrɔfskʲi] ^ⓘ; born 4 June 1952) is a Polish politician and historian who was the fifth president of Poland from 2010 to 2015. Komorowski previously served as Minister of National Defence from 2000 to 2001. As Marshal of the Sejm, Komorowski exercised the powers and duties of acting president following the death of President Lech Kaczyński in a plane crash on 10 April 2010.

Komorowski was then the governing Civic Platform party's candidate in the resulting presidential election, which he won in the second round of voting on 4 July 2010. He was sworn in as president on 6 August 2010. Komorowski thus became the second person to serve on two occasions as Polish head of state since 1918, after Maciej Rataj. On 24 May 2015, Komorowski was defeated in the second round by Andrzej Duda in the 2015 presidential election. As a result, Komorowski was succeeded by Duda on 6 August 2015.

Komorowski was the only president of the Third Polish Republic not to experience a cohabitation while in office. As of 2025, he remains the only Polish president elected with the backing of the Civic Platform party.

Bronisław Maria Komorowski was born in Oborniki Śląskie to Zygmunt Leon Komorowski (1927–1992), professor of African Studies at the University of Warsaw and Jadwiga Komorowska (née Szalkowska) (1921–2025). Bronisław's grandfather Juliusz Komorowski [pl] was the last Komorowski family owner of the Kavoliškis Manor [lt] in the Lithuanian village of Kavoliškis [lt] near Rokiškis. Juliusz Komorowski fluently spoke in the Lithuanian language and taught it to his children. Six generations of the Komorowski family owned Kavoliškis Manor until 1940 when Lithuania was occupied by the Soviets. According to Bronisław Komorowski, while living in Poland his family continued some Lithuanian traditions: consumption of traditional Lithuanian Kūčios dish Kūčiukai and Christmas wafers, also they "decorated the Christmas tree like in Kavoliškis". Furthermore, Komorowski remembered that his grandmother, Maria Magdalena Gorska, sang songs in the Lithuanian language and told him about Lithuania.

From 1957 to 1959 he lived in Józefów near Otwock. From 1959 to 1966 he also attended elementary school in Pruszków. In 1966 he transferred to Warsaw and graduated from Cyprian Kamil Norwid High School no. 24. For many years he was affiliated with the Scout Movement. During his studies he was a Scout instructor in 208 WDHiZ "Parasol" Battalion in Mokotów. He met his future wife through Scouting.

Komorowski recalled that in his adolescence years his father took him near the border, ordered him to kneel and to pray with the Lord's Prayer. Komorowski's father also told him that he should remember that his ancestor's land is behind the barbed wire and that he has to love it.

In 1977 he finished his studies in history at the University of Warsaw. From 1977 to 1980 he was an editor at the journal Słowo Powszechne.

In the Polish People's Republic, Komorowski took part in the democratic movement as an underground publisher and co-operated with Antoni Macierewicz on the monthly Głos (1977–1981).