Fort Ticonderoga, formerly Fort Carillon, is a large 18th-century star fort built by the French at a narrows near the south end of Lake Champlain, in northern New York, in the United States. It was constructed by Canadian-born French military engineer Michel Chartier de Lotbinière, Marquis de Lotbinière between October 1755 and 1757, during the action in the "North American theater" of the Seven Years' War, often referred to in the US as the French and Indian War. The fort was of strategic importance during the 18th-century colonial conflicts between Great Britain and France, and again played an important role during the Revolutionary War.

Fort Carillon, presently known as Fort Ticonderoga, was constructed by Pierre de Rigaud de Vaudreuil, Governor of New France, to protect Lake Champlain from a British invasion. Situated on the lake some 15 miles (24 km) south of Fort Saint Frédéric, it was built to prevent an attack on Canada and slow the advance of the enemy long enough for reinforcements to arrive.