Suncook is a census-designated place (CDP) in Merrimack County, New Hampshire, United States. The population was 5,379 at the 2010 census. Approximately two-thirds of Suncook is located in the town of Pembroke, with the remainder in Allenstown.
The village of Suncook formed along the falls of the Suncook River, which drops 70 feet (21 m) in one-half mile (1 km) just before joining the Merrimack River. Much of the center of the village is occupied by 19th-century factory buildings which once used the river's energy for hydropower. The buildings have now largely been converted to other uses. Much of Suncook's late 19th-century commercial village center has been listed on the National Register of Historic Places.
Suncook was once home to the Suncook Valley Railroad, a shortline railroad company that operated northwest to Concord and northeast to Barnstead. The railroad operated on former Boston and Maine track that was sold to the company. The Suncook Valley Railroad went bankrupt in 1952 and all its track was torn up.
Suncook is located in the southern corner of the town of Pembroke and the western end of the town of Allenstown.