Plymouth Colony (sometimes New Plymouth, or Plymouth Bay Colony) was an English colonial venture in North America from 1620 to 1691. The first settlement of the Plymouth Colony was at New Plymouth, a location previously surveyed and named by Captain John Smith. The settlement, which served as the capital of the colony, is today the modern town of Plymouth, Massachusetts. At its height, Plymouth Colony occupied most of the southeastern portion of the modern state of Massachusetts.

Founded by a group of Separatists and Anglicans, who together later came to be known as the Pilgrims, Plymouth Colony was, along with Jamestown, Virginia, one of the earliest successful colonies to be founded by the English in North America and the first sizable permanent English settlement in the New England region. Aided by Squanto, a Native American of the Patuxet people, the colony was able to establish a treaty with Chief Massasoit which helped to ensure the colony's success. It played a central role in King Philip's War, one of the earliest of the Indian Wars. Ultimately, the colony was merged with the Massachusetts Bay Colony and other territories in 1691 to form the Province of Massachusetts Bay.

Plymouth ⁱ/ˈplɪməθ/ is a city and unitary authority area on the south coast of Devon, England, about 190 miles (310 km) south-west of London. It is situated between the mouths of the rivers Plym to the east and Tamar to the west, where they join Plymouth Sound. Since 1967, the City of Plymouth has included the suburbs of Plympton and Plymstock, which are on the east side of the River Plym.

Plymouth's history goes back to the Bronze Age, when its first settlement grew at Mount Batten. This settlement continued to grow as a trading post for the Roman Empire, until the more prosperous village of Sutton, the current Plymouth, surpassed it. In 1620, the Pilgrim Fathers left Plymouth for the New World and established Plymouth Colony – the second English settlement in what is now the United States of America. During the English Civil War the town was held by the Parliamentarians and was besieged between 1642 and 1646.

Throughout the Industrial Revolution, Plymouth grew as a major commercial shipping port, handling imports and passengers from the Americas, while the neighbouring town of Devonport grew as an important Royal Naval shipbuilding and dockyard town. In 1914 the three neighbouring and independent towns, viz., the county borough of Plymouth, the county borough of Devonport, and the urban district of East Stonehouse were merged to form a single County Borough. The new, merged town took the name of Plymouth which, in 1928, achieved city status. The city's naval importance later led to its targeting and partial destruction during World War II, an act known as the Plymouth Blitz. After the war the city centre was completely rebuilt.