Westvleteren is a village in the province of West Flanders, Belgium. It is a section of the municipality of Vleteren.

Westvleteren is primarily known for the Westvleteren Brewery (Dutch: Brouwerij Westvleteren), a brewery founded in 1838 inside the Trappist Abbey of Saint Sixtus of Westvleteren. Its beers have often been rated best in the entire world. Current brewing capacity is roughly 500,000 cases per year.

Coordinates: 50°55′N 2°43′E / 50.917°N 2.717°E / 50.917; 2.717

The Westvleteren Brewery (Brouwerij Westvleteren) is a Belgian brewery founded in 1838 inside the Trappist Abbey of Saint Sixtus of Westvleteren in the Belgian municipality of Vleteren, not far from the hops-producing town of Poperinge and the medieval city of Ypres. The brewery and its beers are usually referred to as Westvleteren. The brewery's three beers have acquired an international reputation for taste and quality, as well as the limited availability of the beers which are not brewed to normal commercial demands.

Trappist monks from the Catsberg monastery, located in France, founded the St Sixtus monastery in 1831. In 1838, the brewing at Westvleteren commenced. In 1850, some of the monks founded the Notre-Dame de Scourmont monastery, which also brews a Trappist beer. During World Wars I and II, the Westvleteren brewery continued to operate, albeit at a lower capacity. The brewery was the only Trappist one to retain the copper vessels throughout the wars—the other breweries had the copper salvaged by the Germans for their war efforts. In WWI this was primarily due to the abbey not being occupied by the Germans, but instead was caring for wounded allied troops. In 1931, the abbey began selling beer to the general public, having only served beer to guests and visitors up until that time. In 1946, the St. Bernardus brewery in nearby Watou was granted a licence to brew beer under the St Sixtus name. This agreement ended in 1992; St. Bernardus still brews beers of similar styles, but under their own name. That same year, the abbey opened its new brewery to replace the older equipment.