The Sudetes (/suːˈdiːtiːz/ soo-DEE-teez), also known as the Sudeten Mountains or Sudetic Mountains, is a geomorphological subprovince of the Bohemian Massif province in Central Europe, shared by the Czech Republic, Poland and Germany. They consist mainly of mountain ranges and are the highest part of the Bohemian Massif. They stretch from the Saxon capital of Dresden in the northwest across to the region of Lower Silesia in Poland and to the city of Ostrava in the Czech Republic in the east. Geographically the Sudetes are a Mittelgebirge with some characteristics typical of high mountains. Its plateaus and subtle summit relief makes the Sudetes more akin to mountains of Northern Europe than to the Alps.

In the east of the Sudetes, the Moravian Gate and Ostrava Basin separates from the Carpathian Mountains. The Sudetes' highest mountain is Sněžka (Polish: Śnieżka) at 1,603 m (5,259 ft), which is also the highest mountain of the Czech Republic, Bohemia, Silesia, and Lower Silesian Voivodeship. It lies in the Giant Mountains on the border between the Czech Republic and Poland. Praděd (1,491 m/4,893 ft) in the Hrubý Jeseník mountains is the highest mountain of Moravia. Lusatia's highest point (1,072 m/3,517 ft) lies on Smrk mountain in the Jizera Mountains, and the Sudetes' highest mountain in Germany, which is also the country's highest mountain east of the river Elbe, is Lausche (793 m/2,600 ft) in the Lusatian Mountains. The most notable rivers rising in the Sudetes are the Elbe, Oder, Spree, Morava, Bóbr, Lusatian Neisse, Eastern Neisse, Jizera and Kwisa. The highest parts of the Sudetes are protected by national parks; Karkonosze and Stołowe (Table) in Poland and Krkonoše in the Czech Republic.

In the west, the Sudetes border with the Elbe Sandstone Mountains. The westernmost point of the Sudetes lies in the Dresden Heath (Dresdner Heide), the westernmost part of the West Lusatian Hill Country and Uplands, in Dresden.

The Sudeten Germans (the German-speaking inhabitants of Czechoslovakia) as well as the Sudetenland (the border regions of Bohemia, Moravia, and Czech Silesia they inhabited) are named after the Sudetes.

The name Sudetes is derived from Sudeti montes, a Latinization of the name Soudeta ore used in the Geographia by the Greco-Roman writer Ptolemy (Book 2, Chapter 10) c. AD 150 for a range of mountains in Germania in the general region of the modern Czech Republic.

There is no consensus about which mountains he meant, and he could for example have intended the Ore Mountains, joining the modern Sudetes to their west, or even (according to Schütte) the Bohemian Forest (although this is normally considered to be equivalent to Ptolemy's Gabreta forest). The modern Sudetes are probably Ptolemy's Askiburgion mountains. It has also been proposed that Ptolemy's Askiburgion and Sudeti are the same mountains, with one being measured from the north, and one from the south.

Ptolemy wrote "Σούδητα" in Greek, which is a neuter plural. Latin mons, however, is a masculine, hence Sudeti. The Latin version, and the modern geographical identification, is likely to be a scholastic innovation, as it is not attested in classical Latin literature. The meaning of the name is not known. In one hypothetical derivation, it means Mountains of Wild Boars, relying on Indo-European *su-, "pig". A better etymology perhaps is from Latin sudis, plural sudes, "spines", which can be used of spiny fish or spiny terrain.

The Sudetes are usually divided into: