Massena is a town in St. Lawrence County, New York, United States. Massena is along the county's northern border, just south of the St. Lawrence River and the Three Nations Crossing of the Canada–United States border. The population was 12,433 at the 2020 census. The town of Massena contains a village also named Massena.

Massena was established in 1792 by Anable Faucher. The settlement was initially called Nikentsiake by the Mohawk Indians, translating to "where the fish live." Massena was one of the first towns settled in St. Lawrence county, but was not incorporated until 1802 when it was formed from the town of Lisbon. The town and its village are named after André Masséna, a general and Marshal to Napoleon during the Napoleonic Wars.

The town boasted the Massena Springs, a pair of sulfur springs, one hot and the other cold, reputed to possess healing powers known to the Native Americans before European settlement. In 1820, an Army veteran, Captain John Polley, hoping to capitalize on the properties, opened a hotel and began to advertise them. By 1858, three hotels, numerous rental cottages, a bathing house, and a plant that bottled and sold the spring water, had been built. By about 1900, the Springs' status as a popular resort had faded.

Up until the 1880s, the town was predominantly agricultural, mainly home to butter and cheese production. The first small mills were built in the 1830s, harnessing the Grasse River to turn their wheels. They included a saw mill, stone-cutter, and a tannery. In 1833, New York State Legislature approved a canal that would bypass a troublesome rapids hindering navigation on the St. Lawrence by linking the Grasse and St. Lawrence Rivers. However, the British North American government preempted this project by building the Cornwall Canal on the Canadian side of the River, completed in 1843.

The Massena Canal project was revived at the end of the century and completed in 1898, finally connecting the Grasse River and St. Lawrence River. A powerhouse built in 1900 provided hydroelectric power to the town. The new canal attracted the Pittsburgh Reduction Company (later Alcoa). This influx of industry workers transformed former health retreat hotels into housing for the burgeoning workforce. The Massena Power Canal was closed in 1958.

In 1928 the town was the scene of the antisemitic Massena blood libel. The town's Jews were falsely accused of kidnapping and ritual murder of a girl.

In the 1950s, the New York Power Authority was established, leading to the creation of the St. Lawrence-Franklin D. Roosevelt Power Project. Spanning the St. Lawrence River, the hydropower plant was capable of generating over 900,000 kilowatts of electricity. Simultaneously, the 1950s witnessed the development of the St. Lawrence Seaway, a monumental American-Canadian navigational project. This system of locks and gates facilitated the movement of boats through the river, connecting the Great Lakes to the Atlantic Ocean. With the completion of the Seaway and Power Project, Massena experienced a significant expansion at the Alcoa plant, solidifying its status as the oldest continuously operating aluminum production facility in the Western Hemisphere.

The 1980s saw the establishment of the St. Lawrence Centre Mall and St. Lawrence strip mall complex, fostering a regional retail hub, attracting Canadian shoppers.