The Seneca are a group of indigenous Iroquoian-speaking people native to North America who historically lived south of Lake Ontario.

They are the nation located farthest to the west within the Six Nations or Iroquois League (Haudenosaunee) in New York before the American Revolution.In the twenty-first century, more than ten thousand Seneca live in the United States, which has three federally recognized Seneca tribes.

Two are in New York: the Seneca Nation of New York, with two reservations in western New York near Buffalo, and the Tonawanda Band of Seneca Native Americans.

The Seneca-Cayuga Nation is located in Oklahoma, where their ancestors were relocated from Ohio during Indian Removal.

Approximately one thousand Seneca live in Canada, near Brantford, Ontario, at the Six Nations of the Grand River First Nation.

They are descendants of Seneca who resettled there after the American Revolution, as they had been allies of the British and forced to cede much of their lands.