The Seneca (//) (Seneca: Onödowáʼga:, "Great Hill People") are a group of Indigenous Iroquoian-speaking people who historically lived south of Lake Ontario, one of the five Great Lakes in North America. Their nation was the farthest to the west within the Six Nations or Iroquois League (Haudenosaunee) in New York before the American Revolution.
|Regions with significant populations|
| United States|
( New York, Oklahoma)
|Niagara Falls Territory||Ontario|
|Longhouse (Handsome Lake), Kai'hwi'io, Kanoh'hon'io, Kahni'kwi'io, Christian denominations|
|Related ethnic groups|
|Onondaga Nation, Oneida Nation, Tuscarora Nation, Mohawk Nation, Cayuga Nation, other Iroquoian peoples|
In the 21st century, more than 10,000 Seneca live in the United States, which has three federally recognized Seneca tribes. Two of them are centered in New York: the Seneca Nation of Indians, with two reservations in western New York near Buffalo; and the Tonawanda Seneca Nation. The Seneca-Cayuga Nation is in Oklahoma, where their ancestors were relocated from Ohio during the Indian Removal. Approximately 1,000 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.