Fogartach mac Cummascaig (died 786) was King of South Brega of the Uí Chernaig sept of Lagore of the Síl nÁedo Sláine branch of the southern Ui Neill.
Fogartach participated in 781 in the Battle of the Rig fought between the Síl nÁedo Sláine and the Uí Garrchon branch of the Laigin with his cousin Máel Dúin mac Fergusa (died 785), who was King of Loch gabor at that time.
In 786 Febordaith, the abbot of Tuilén was killed apparently by the Síl nÁedo Sláine.
[3] The high king Donnchad Midi (died 797) avenged this by attacking and defeating the forces of the Síl nÁedo Sláine at the Battle of Lia Finn or Tuilén and Fogartach was slain along with his kinsmen.
His son Cummascach mac Fogartaig (died 797) was also King of South Brega.