Heber MacMahon (Irish Éimhear Mac Mathúna) (1600 – 1650) was bishop of Clogher and general in Ulster.
[3] He was ordained a priest in 1625 and appointed as Vicar apostolic of the Diocese of Clogher by a papal brief on 17 November 1627.
[4] He worked closely with Owen Roe O'Neill throughout the 1640s and liaised with Giovanni Battista Rinuccini after his arrival in 1645.
Following the mysterious death of Owen Roe O'Neill on 6 November 1649, the leadership of the Ulster army of 5,000 foot soldiers and 600 cavalry was entrusted to Bishop McMahon by the Earl of Ormonde.
In 1650 McMahon took Dungiven and massacred the Protestant inhabitants, but the Irish forces were then routed by Cromwell’s army at the battle of Scarrifholis, near Letterkenny, in June of that same year.