Kings Langley is a village, former manor and civil parish in Hertfordshire, England, 21 miles north-west of Westminster in the historic centre of London and to the south of the Chiltern Hills. It now forms part of the London commuter belt. The village is divided between two local government districts by the River Gade with the larger western portion in the Borough of Dacorum and smaller part, to the east of the river, in Three Rivers District. It was the location of Kings Langley Palace and the associated King's Langley Priory, of which few traces survive.
It is 2 mi situated south of Hemel Hempstead and 2 mi north of Watford.
The earliest mention in surviving documents of the manor of Langalega is in a Saxon charter dated circa 1050. It appears as Langelai in the Domesday Book of 1086, and is recorded as Langel' Regis in 1254. The name means "long wood or clearing".