Rybnik (Polish pronunciation: [ˈrɨbɲik] ^ⓘ; Silesian: Rybńik) is a city in southern Poland, in the Silesian Voivodeship, around 38 km (24 mi) southwest of Katowice, the region's capital, and around 19 km (12 mi) from the Czech border. It is one of the major cities of the Katowice-Ostrava metropolitan area with a population of 5.3 million and the main city of the so-called Subregion Zachodni, previously also known as the Rybnik Coal Area. With a population of 135,994 as of January 1, 2022, it is the 25th most-populous city in Poland.

Rybnik is the center of commerce, business, transportation and culture for the southwestern part of the Silesian Voivodeship, a consolidated city-county and the seat of a separate suburban Rybnik county. Rybnik is particularly recognized for its contributions to music, with the Szafrankowie School of Music musicians such as Henryk Górecki or Lidia Grychtołówna, among others. It is also a seat of the Rybnik Philharmonic Orchestra.

The name Rybnik derives from an old Slavic word rybnik, meaning a pond (Czech language still uses it, while in Polish the modern word is staw), which was located in the place of the current market square. In the middle ages, three settlements merged into one town, with a Magdeburg rights location dating back to 1308. Fishing, trade and artistry were the main industries. Rybnik's development accelerated in late 19th century upon discovery of rich coal fields, and continued until the 1980s. Since the 1990s, the city attempts to diversify its economy with commerce, health care and business industries.

The city's name derives from the Proto-Slavic word for "fish" (ryba) and meant "fishpond" in the Old Polish language. The name highlights the importance of fish farming for the city's economy in the Middle Ages, which is reflected in its coat of arms until this day.

The city's origins can be traced back into the 9th and 10th century, when three Slavic settlements existed on Rybnik's present-day territory which eventually merged to form one town. It became part of the emerging Polish state under its first historic ruler Mieszko I in the 10th century. In the course of the medieval eastward migration of German settlers (Ostsiedlung), Rybnik, as many other Polish settlements, was incorporated (granted city status and right) according to the so-called Magdeburg Law at some point before 1308 (the exact date remains unknown). This, however, is not to be confused with a change in national affiliation; Rybnik continued to be part of the Kingdom of Poland, until most of Silesia became a fiefdom of the Bohemian Crown in 1327, however Rybnik was still ruled by local Polish dukes of the Piast dynasty until 1336.

The city continued to grow and developed into a regional trade centre. In the 15th century, the Hussites devastated the city, before being eventually defeated in a decisive battle on a hill nearby in 1433, with Poles and Czechs fighting on both sides. Around 1469 the city passed under Hungarian suzerainty, and in 1490 it fell back to Bohemia. From 1521 Rybnik was again ruled by Polish Piast dukes, as it was integrated with the Duchy of Opole and Racibórz, before in 1532 it eventually was incorporated into Bohemia, which itself came under the authority of the Habsburg crown. Then the city became the capital of a state country held by various noble families, including the Polish Węgierski family of Rola coat of arms from 1682 until the state country's dissolution in 1788.

At the beginning of the War of the Austrian Succession between Frederick II of Prussia (the Great) and the Habsburg empress Maria Theresa of Austria, most of Silesia, including Rybnik, was annexed by Prussia in 1740, which Austria eventually recognized in 1763. In the 18th century, Rybnik belonged to the tax inspection region of Prudnik. Coal mining gained importance for Rybnik's economy as early as the 18th century. In 1871, Prussia, including Rybnik, merged into the German Empire, the first modern German nation state. At this point, Poland had already ceased to exist as an independent state, having been divided between Prussia, Austria and Russia in the Third Partition of Poland of 1795.

With the intensification of Germanization and anti-Polish policies in the German Empire in the late 19th and early 20th century, the ethnically mixed region of Upper Silesia became affected by growing tensions between German nationalists and indigenous Poles. After the end of World War I in 1918, the Polish state was finally restored. Amidst an atmosphere of ethnic unrest, the Polish Silesian Uprisings broke out, the first of which (in 1919) was centered on Rybnik, and the Upper Silesia plebiscite was held in 1921 to determine the future state affiliation. The lowest share of pro-German votes was registered in the districts of Rybnik (34.7%) and Pszczyna (25.9%). However, in the city of Rybnik, 70.8% of the votes were in favour of Germany. The city and the larger part of the Rybnik district were attached to Poland. Rybnik thus became Polish-ruled for the first time since 1788.