Ulster refers primarily to the province of Ulster, one of the four provinces on the island of Ireland.

The name Ulster also appears in some other contexts originally named in honour of the Irish province:

• Ulster, Pennsylvania, United States of America
• Ulster County, New York, United States of America
• Ulster, New York, a town in Ulster County, NY.
• Ulster Park, New York , United States of America
• Northern Ireland, sometimes called Ulster by its Unionist community.

See also: Irish Place Names in Other Countries

An ulster is also a kind of overcoat.