The Sunni Triangle is a densely-populated region of Iraq to the northwest of Baghdad that is inhabited mostly by Sunni Muslim Arabs.

The roughly triangular area's corners are usually said to lie near Baqubah (on the east side of the triangle), Baghdad (on the South side), Ramadi (on the west side) and Tikrit (on the north side). Each side is approximately 125 miles long. The area also contains the cities of Samarra and Fallujah.

The area was a center of strong support for former Iraqi president Saddam Hussein's government; starting in the 1970s many government workers, politicians, and military leaders came from the area. Saddam himself was born just outside Tikrit.

After the 2003 invasion of Iraq, the area became a focus of armed Sunni opposition to Coalition rule. It was widely predicted in the Western press that Saddam would seek shelter from Sunni supporters and on December 13, 2003, he was captured in a raid on the village of ad-Dawr about 15 km south of Tikrit.

The term "Sunni triangle" was used intermittently from the 1970s among academic Iraq specialists, usually to differentiate it from the northern and southern parts of the country. An early use in mainstream media is a San Francisco Chronicle article of September 14, 2002 in which former United Nations weapons inspector Scott Ritter says: "We may be able to generate support for an invasion among some of the Shiites and some of the Kurds, but to get to Baghdad you must penetrate the Sunni Triangle." However, it did not achieve widespread use until a New York Times article of June 10, 2003 popularised the term in a report on "a new U.S. effort to quell nascent armed resistance in Sunni Muslim-dominated areas north and west of Baghdad [in an] area known as the 'Sunni triangle'." It has since become virtually ubiquitous in reports on the US-led coalition's efforts to control the region.