This interesting and unusual surname is of Old Gaelic origin, and is a variant of "O'Donnellan", itself the Anglicized form of the Gaelic "O'Domhnallain", which is composed of the Gaelic prefix "O", meaning "male descendant of", and the personal name "Domhnall", Donnell, who was the lord of Clan Breasail, from whom bearers of the name claim descent. The O'Donnellans were a sept of the Ui Maine who were settled in the south-eastern part of County Galway, where the placename Ballydonnellan erpetuates their connection with the district between Ballinasloe and Loughrea. The original castle of Ballydonnellan is reputed to have been built by them in 936 A.D., and was rebuilt in 1412, after being destroyed by fire. The family was from the 11th Century a notable bardic family seated at Ross-O'Donelan, near Elphin, County Roscommon, and many of the family are mentioned in the Annals of the Four Masters, and Annals of Connacht. The name was introduced into England by Irish famine immigrants in the last century. Early recordings include: the christening of John Donelan on October 2nd 1629, at St. John the Evangelist, Dublin; the marriage of Mary Danlon and John Stedman on January 4th 1763, in Limerick; and the birth of a daughter, Mary, to Hugh and Bridget Donlon, at Williamstown, County Galway, on January 6th 1864. The first recorded spelling of the family name is shown to be that of Brian Mac Owen O'Donnellan, which was dated circa 1610, in the "Annals of the Four Masters", during the reign of King James 1 of England and V1 of Scotland, 1603 - 1625. Surnames became necessary when governments introduced personal taxation. In England this was known as Poll Tax. Throughout the centuries, surnames in every country have continued to "develop" often leading to astonishing variants of the original spelling.