Dungannon (Dún Gaynainn in Irish) is a town in County Tyrone in Northern Ireland (United Kingdom) . It has about 10,000 inhabitants, and is the centre of a the Dungannon and South Tyrone local government area.

Its Royal School is said to be the oldest school in Ireland. It was one of several royal schools chartered in 1614 by King James I with the intended purpose "that there shall be one Free School at least appointed in every County, for the education of youth in learning and religion." These schools provided an English style education to the sons of landed settlers in Ireland, most of whom were of Scottish or English descent. The Royal School Dungannon was established in 1614 at Mountjoy near Lough Neagh. A royal charter of 13th May - records the appointment of John Bullingbroke as the first Headmaster.

The once thriving linen industry has largely been replaced by glass-blowing, and the Tyrone Crystal factory is a major visitor attraction in Northern Ireland. Dungannon also had brick making industry using Coalisland fireclay.

Dungannon was one corner of the infamous murder triangle.

See also: List of towns in Northern Ireland