Muiredach (Old Irish), Muireadhach or Muireach, anglicized variously to Murdoch, Murtagh, Murdac, Mordacq and other forms, is a Goidelic name (meaning "chieftain") popular in Scotland and Ireland in the Middle Ages:
Muiredach Bolgrach, mythological Irish king
Muiredach Tirech, legendary high-king of Ireland
Muiredach mac Eógain (died 489), legendary early king of Ailech
Muiredach Muinderg (died 489), legendary king of the Ulaid
Muiredach of Killala, reputed early Irish saint
Muiredach Muillethan (died 702), king of Connaught
Muiredach mac Ainbcellaig (died c. 770), king of Dál Riata
Muiredach mac Murchado (died 760), king of Leinster
Muiredach mac Brain (died 818) (8th-century–818), king of Leinster
Muiredach mac Ruadrach (8th-century–829), king of Leinster
Muiredach mac Eochada (died 839), king of the Ulaid
Muiredach mac Brain (died 885), king of Munster
Muiredach mac Eochocáin (died 895), king of the Ulaid
Muireadhach Ua Carthaigh (died 1067), Chief Poet of Connacht
Muireadhach Ua Dubhthaigh, Archbishop of Connacht
Muireadhach Ua Flaithbheartaigh (died 1121), King of Iar Connacht
Muiredach (ealdorman) (fl. 958–963), ealdorman
Muireadhach I, Earl of Menteith (fl. 12th-century–13th-century), Scottish mormaer
Muireadhach Albanach (fl. early 12th-century–13th-centuryth century), Gaelic poet and crusader
Muireadhach II, Earl of Menteith (died c. 1230), Scottish mormaer
Muireadhach III, Earl of Menteith (died 1332), Scottish mormaer
Muireadhach of Inchaffray (died 1340s), Scottish abbot
Muireadhach Sdíbhard or Muireadhach IV, Earl of Menteith (died 1425), Scottish prince
