The Connecticut Colony or Colony of Connecticut was an English colony located in British America that became the U.S. state of Connecticut. Originally known as the River Colony, it was organized on March 3, 1636 as a haven for Puritan noblemen. After early struggles with the Dutch, the English gained control of the colony permanently by the late 1630s. The colony was later the scene of a bloody war between the English and Indians, known as the Pequot War. It played a significant role in the establishment of self-government in the New World with its legendary refusal to surrender local authority to the Dominion of New England, an event known as the Charter Oak incident which occurred at Jeremy Adams' inn & tavern.

Two other English colonies in the present-day state of Connecticut were merged into the Colony of Connecticut: Saybrook Colony in 1644 and New Haven Colony in 1662.

Thomas Hooker, a prominent Puritan minister, and Governor John Haynes of the Massachusetts Bay Colony, who led 100 people to present day Hartford in 1636, are often considered the founders of the Connecticut colony. The sermon Hooker delivered to his congregation on the principles of government on May 31, 1638 influenced those who would write the Fundamental Orders of Connecticut later that year. The Fundamental Orders may have been drafted by Roger Ludlow of Windsor, the only trained lawyer living in Connecticut in the 1630s, and were transcribed into the official record by the secretary, Thomas Welles.

Connecticut (ⁱ/kəˈnɛtɨkət/) is a state in the New England region of the northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, and the state of New York to the west and the south (with which it shares a water boundary in Long Island Sound).

Connecticut is named for the Connecticut River, the major U.S. river that approximately bisects the state. Its capital city is Hartford. Much of southern and western Connecticut (along with the majority of the state's population) is part of the New York metropolitan area; three of Connecticut's eight counties are statistically included in the New York City combined statistical area, the same area is widely referred to as the Tri-State area. Connecticut's center of population is in Cheshire, New Haven County, which is also located within the Tri-State area.

Connecticut is the 3rd least extensive, the 29th most populous, and 4th most densely populated of the 50 United States. Called the Constitution State, Nutmeg State, and "The Land of Steady Habits", Connecticut was influential in the development of the federal government of the United States.