This is both a royal and noble Irish surname. Recorded in many forms including O'Donegan, Donegan, Dunican, Dungan, Doonican, and the rare and unusual County Cork spellings of Dingivan and Dinnine, this clan is divided into four branches or septs. The origination is from the 10th century kings of a region called Fernmhagh, in what is now County Westmeath. As befits a "royal" family, their numbers, are quite small. In the 20th century only some two hundred families are recorded in the whole of Ireland. This was not so in the seventeenth century and earlier, when the O'Donegans held the manor of Kildrought. Thomas Donegan, from this family being earl of Limerick, and creater of the 1686 Don(e)gan Charter, whereby the city of New York was passed by the Dutch to Britain.In the barony of Rathconrath, County Westmeath, over forty families called O'Donegan were recorded in the 1659 "Petty's" cenus of Irelandand there was also an appreciable number of nameholders in both County Cork and County Sligo. The County Cork sept were once a powerful clan in their own right, the area around the baronies of Orrery and Duhallow in North West Cork being known as "O'Donegans country". The Donegans were firm supporters of the Stewart monarchs. In 1691 the earl of Limerick supported the exiled James 11, the last king of Ireland, and paid for his support with the loss of his lands. Thereafter the clan seems to have gone into decline, and many nameholders left for American and England during the great potato famine of 1846 - 48. The first known name holder is probably Donnadh O' Donnagain, the king of Fernmagh, County Monaghan. According to the ancient rolls called "Loch Ce", he died in the year1029.