Brentwood is a town in Rockingham County, New Hampshire, United States. As of the 2010 census, the town had a total population of 4,486. Brentwood has been the county seat of Rockingham County since 1997. It is drained by the Piscassic, Little and Exeter rivers.
Long before Europeans settled the area, Brentwood was home to the Pennacook Abenaki tribes which farmed, fished and hunted there. Two main foot trails ran through the town, one along the Exeter River, where arrowheads and other stone and wooden artifacts have been found. At Pickpocket Dam, this pathway joined with the historic Pentucket Trail leading to Haverhill, Massachusetts, or points north.
The town was once a part of Exeter known as Brentwood Parish. It was named after Brentwood, Essex, originally called "Burnt Wood", where, in 1177, King Henry II granted permission for of the king's forest to be cut, burned and cultivated. As early as 1738, residents living in the southwestern portion of Exeter, now Brentwood and Fremont, petitioned to be set off, but were denied. On 26 June 1742, however, permission was granted, and Brentwood was incorporated by Colonial Governor Benning Wentworth.
But almost from the beginning, a dispute arose between districts regarding the placement of a meetinghouse. It divided the community. Consequently, Gov. Wentworth, acting without approval of the General Assembly, in 1744 issued a King's Patent to establish a new town within Brentwood called Keeneborough Parish, named after his friend, Sir Benjamin Keene (1697–1757), English minister to Spain. Factions reconciled in 1750, when Keeneborough reunited with Brentwood.
Brentwood was marginally involved in the Exeter incident, a UFO sighting in 1965. While the main incident was reported in nearby Kensington, a young Brentwood couple, Jack Sidoway and Lindsey Webb, also reported having seen lights while parked out in a field. They claimed that these lights followed them as they got out of their car and ran through a field in order to "try to get away from the lights." It is thought that their claims were not taken seriously due to their age. Also as this account is from Brentwood and not Exeter it was not included in the official Exeter documents, and as such were overlooked.