The Dillons (Diolun) came to Ireland with the Anglo-Norman invasion. Sir Henry Dillon received from King John large grants of land covering much of Westmeath, known in later times as Dillon’s Country. His descendants became barons of Kilkenny West, a barony on the western side of County Westmeath. A branch settled in Mayo. The Dillons were high in the service of the Stewarts, and after the fall of the Stewarts, they became famous as colonel-proprietors of Dillon’s Regiment in the French service. One of them was made a French count in 1711.

The Fagans (Pagan) appear as early as 1200 as extensive property holders in the city of Dublin. Soon afterwards they are found seated at Feltrim, County Dublin. Branches settled in Cork and Kerry: The Cork branch descends from Christopher Fagan, who took refuge there for political reasons in 1497, while the Kerry branch became famous in the service of France in the eighteenth century.

The Fitzgeralds (Mac Gearailt) called collectively the "Geraldines," descend from Gerald, Constable of Pembroke in Wales, whose wife was Nest, daughter of Rhys Ap Tewdwyr, King of South Wales. Gerald flourished in the early part of the twelfth century. His son, Maurice Fitzgerald, ancestor of the Irish FitzGeralds, was one of the allies of Strongbow, the leader and organizer of the Anglo-Norman invasion. Maurice received grants of land in several parts of Ireland, and his descendants were, with the Burkes and Butlers, among the most powerful of Norman families in Ireland, and members of the family often filled high offices in Ireland under the English Crown. The Leinster branch of the family held for many centuries the Earldom of Kilare, while the Munster branch held the Earldom of Desmond. A branch of the Fitzgeralds, the Barrons (Barun) of Burnchurch, County Kilkenny, assumed the surname of Barron from their title in those parts, and remain a highly respectable family in that area and Waterford. The MacMorises (Mac Muiris) or Fitzmaurices were a branch of the Geraldines who became lords of Lixnaw in County Kerry, and became famous for their resistance to the English invaders of the sixteenth century. In 1333 the then Earl Palatine of Desmond created three hereditary knights, two of whom were sons of a John Fitzgerald. The two lineal male descendants and heirs of these two brothers are still known respectively as the Knight of Glin and the Knight of Kerry.

The MacGibbons (Mac Giobuin) or Fitzgibbons descend from Gilbert de Clare, who about 1300 possessed the manor or Mahoonagh and other valuable estates in southeastern County Limerick. The head of this family is the White Knight, one of three hereditary knights so named in 1333 by the Earl of Desmond. A branch of the family settled in County Cork, where they were chiefs of a territory known as Clangibbon.