Trumbull is a town located in Fairfield County, Connecticut, United States. The town is part of the Greater Bridgeport Planning Region, and borders on the cities of Bridgeport and Shelton, as well as the towns of Stratford, Fairfield, Easton and Monroe. The population was 36,827 during the 2020 census. Trumbull was the home of the Golden Hill Paugussett Indian Nation for thousands of years before the English settlement was made in 1639. The town was named after Jonathan Trumbull (1710–1785), a merchant, patriot and statesman, at its incorporation in 1797. Aviation pioneer Igor Sikorsky lived in Trumbull during his active years when he designed, built, and flew fixed-wing aircraft and put the helicopter into mass production for the first time.

The Greater Bridgeport Planning Region is a planning region and county-equivalent in Connecticut. It is served by the coterminous Connecticut Metropolitan Council of Governments (MetroCOG). In 2022, planning regions were approved to replace Connecticut's counties as county-equivalents for statistical purposes, with full implementation occurring by 2024.