Winchester (, US also ) is a cathedral city in Hampshire, England. The city lies at the heart of the wider City of Winchester, a local government district, at the western end of the South Downs National Park, on the River Itchen. It is 60 miles (97 km) south-west of London and 14 miles (23 km) from Southampton, its nearest city. At the 2011 census, Winchester had a population of 45,184. The wider City of Winchester district, which includes towns such as Alresford and Bishop's Waltham, has a population of 116,595. Winchester is the county town of Hampshire and contains the head offices of Hampshire County Council.

Winchester developed from the Roman town of Venta Belgarum, which in turn developed from an Iron Age oppidum. Winchester was one of the most important cities in England until the Norman conquest in the eleventh century. It has since become one of the most expensive and affluent areas in the United Kingdom.

The city's major landmark is Winchester Cathedral. The city is also home to the University of Winchester and Winchester College, the oldest public school in the United Kingdom still using its original buildings.