Mariupol (UK: , US: (listen); Ukrainian: Маріу́поль [mɐr⁽ʲ⁾iˈupolʲ] (listen); Russian: Мариу́поль, IPA: [mərʲɪˈupəlʲ]; Greek: Μαριούπολη) is a city in Donetsk Oblast, Ukraine. Since May 2022, Mariupol has been occupied by Russian forces. It is situated on the northern coast (Pryazovia) of the Sea of Azov, at the mouth of the Kalmius River. Prior to the Russian invasion of Ukraine, it was the tenth-largest city in the country and the second-largest city in Donetsk Oblast, with an estimated population of 425,681 people in January 2022, however Ukrainian authorities estimate its current population to be approximately 100,000.

Historically, the city of Mariupol was a centre for trade and manufacturing, and played a key role in the development of higher education and many businesses while also serving as a coastal resort on the Sea of Azov. In 1948, Mariupol was renamed Zhdanov after Andrei Zhdanov, a native of the city who had become a high-ranking official of the Communist Party of the Soviet Union and a close ally to Joseph Stalin. The name was part of a larger effort to rename cities after high-ranking political figures in the Soviet Union. The historic name was restored in 1989. Mariupol was founded on the site of a former encampment for Cossacks, known as Kalmius, and was granted city rights within the Russian Empire in 1778. It played a key role in the Stalin-era industrialization; it was a centre for grain trade, metallurgy, and heavy engineering—including the Illich Iron and Steel Works and the Azovstal Iron and Steel Works.

Beginning on 24 February 2022, the three-month-long siege of Mariupol by Russian forces largely destroyed the city, for which it was given the title "Hero City of Ukraine" by the Ukrainian government. On 16 May 2022, all Ukrainian troops who remained in Mariupol surrendered at Azovstal Iron and Steel Works, as the Russian military secured complete control over the city by 20 May 2022.