Selangor (Jawi: سلنجور, population 4.1 million) is one of the 13 states of Malaysia. It is on the west coast of Peninsular Malaysia and is bordered by Perak to the north, Pahang to the east, Negri Sembilan to the south and the Strait of Malacca to the west. It totally surrounds the federal territories of Kuala Lumpur and Putrajaya.

The name Selangor is said to come from the Malay word selangau, 'a fly' (Musca vicina), most probably due to the abundance of flies in the marshes along the Selangor River in the state's north-west.