The O’Madden Family, derive their name from Ó Madadhán or Ó Madadihín the diminutives of madadh, a dog. The O’Maddens are a branch of the Uí Maine, and of the same stock as the O’Kellys; and derive their descent from Madadhan, the son of Gadhra Mór, chief of Uí Maine from 1014 to 1027. Madadhan was slain in 1008 but his descendants became chiefs of Síol Anmchadha, the descendants of Anmchadh, a branch of the Uí Maine, who became independent of their parent body towards the middle of the eleventh century. This group gave their name to the territory of Síol Anmchadha, a region that corresponds with the present Galway barony of Longford, and the parish of Lusmagh in County Offaly.
The O’Maddens retained their lordship of Síol Anmchadha under the De Burgo supremacy. Donal O’Madden, “captain of his nation”, settled his manor and castle of Longford and all of his other estates in the county, on his son and heir, Anmchadha, or Ambrose, O’Madden, in 1612. Ambrose died in 1637 and was succeeded by his son, John who lost the O’Madden holdings after the Cromwellian wars. In 1677 some of the confiscated lands were restored under the Act of Settlement. Five of the O’Maddens were attainted after 1691, supporters of the defeated James II. Variants on this surname include O’Maddane, O’Maddine, O’Maddin and Madden. The Maddens of Baggotrath, near Dublin, and of Athgarret, in County Kildare, and the Maidgans of Clare and Limerick are all descended from the Ó Madain of Galway. The Maddens of Maddenton, County Kildare, however, are of English origin while the Maddens of Mayo derive their name from an incorrect Anglicization of Mac and Mhadaid.