Southbury is a town in western New Haven County, Connecticut, United States. Southbury is north of Oxford and Newtown, and east of Brookfield.

Southbury comprises sprawling rural country areas, suburban neighborhoods, and historic districts. It is a short distance from major business and commercial centers, and is within 80 miles (130 km) of New York City and 40 miles (64 km) of Hartford; the latter the capital of Connecticut.

Southbury is the only community in the country with the name “Southbury”, which is why the town seal reads Unica Unaque, meaning “The One and Only.”

The town of Southbury was one of several towns formed out of a parcel of land purchased from the Paugussett Native Americans in 1659. Southbury was originally part of Woodbury, which was settled in 1673. A meetinghouse for the Southbury Ecclesiastical Society was built in 1733, and in 1845 the town of Southbury was incorporated. Although incorporated as part of Litchfield County, Southbury has been in New Haven County for most of its existence.