Chichester is a town in Merrimack County, New Hampshire, United States. The population was 2,523 at the 2010 census.
Chichester was granted in 1727 to Nathaniel Gookin and others, and was named for Thomas Pelham-Holles, 1st Duke of Newcastle-upon-Tyne, Earl of Chichester and England's Secretary of State for the Southern Department. The first settlement was commenced by Paul Morrill, in 1758.
According to the United States Census Bureau, the town has a total area of 21.2 square miles (55 km2), of which 21.1 sq mi (55 km2) is land and 0.1 sq mi (0.26 km2) is water, comprising 0.52% of the town. The highest point in Chichester is an unnamed summit at 1,015 feet (309 m) above sea level, midway between Garvin Hill (985 ft or 300 m) to the east and Plausawa Hill (1,000 ft or 300 m) to the west in neighboring Pembroke. All three summits are less than one mile apart. Chichester lies fully within the Merrimack River watershed.
As of the census of 2000, there were 2,236 people, 823 households, and 637 families residing in the town. The population density was 106.1 people per square mile (41.0/km2). There were 849 housing units at an average density of 40.3 per square mile (15.6/km2). The racial makeup of the town was 98.17% White, 0.18% African American, 0.36% Native American, 0.13% Asian, 0.18% from other races, and 0.98% from two or more races. Hispanic or Latino of any race were 0.67% of the population.