Ventspils (ventspi:ls, ; Windau) is a city in northwestern Latvia on the coast of the Baltic Sea. It is named after the Venta River, which passes through the city. Ventspils had a population of 43,806 in 2006.

Ventspils developed from a castle of the Livonian Order and was first mentioned in chronicles in 1290. It was chartered in 1314 and became an important mercantile city of the Hanseatic League.

Ventspils is an important ice-free port. Large amounts of oil and other mineral resources from Russia are loaded aboard ships at Ventspils. The revenue from port services has made Ventspils the wealthiest city in Latvia.

Thirty kilometres north of Ventspils is the ex-Soviet radioastronomy installation VIRAC (Ventspils Starptautiskais Radioastronomijas Centrs or Ventspils International Radio Astronomy Centre). The existence of the Centrs was unknown to most Latvians until the withdrawal of the Soviets at the end of occupation in 1994.

The city has a university college, Ventspils Augstskola, and a basketball team that has won the Latvian championship in the last several years. In the 2001/2002 season, the team took third place in the North European Basketball League (NEBL). Ventspils also has a football team in FK Ventspils who compete in the Virsliga. In the 2006 season the team has won the Latvian championship for the first time.

Ventspils has a Blue Flag Beach.

Ventspils Airport, one of the three international airports in Latvia, is located in the city. Ventspils High Technology Park provides infrastructure and services to IT and electronics companies.

Ventspils' mayor is Aivars Lembergs.

In 2004 Ventspils was a host city for a multi-national (United States, United Kingdom, Poland, Sweden, Russia, Latvia, Denmark, Finland, Norway) naval exercise called Baltic Operations (BALTOPS). The force was led by the guided missile cruiser USS Anzio. Anzio was the first American warship to visit the port of Ventspils since Latvian independence was declared.