Muirchertach Ua Briain (anglicised as Murtaugh O'Brien; c. 1050 – c. 10 March 1119, son of Toirdelbach Ua Briain and great-grandson of Brian Boru, was King of Munster and later self-declared High King of Ireland.
- Occupation
- monarch
- Position held
- King of Munster
- Born
- 1050
- Died
- March 10, 1119, 1119