From JCHAS:

Courceys. So-named from the de Courceys. The founder of this family, John de Courcey, was one of the three Anglo-Norman adventurers who came over with William Fitz-Adelm to seek their fortunes in Ireland, and one of the first Anglo-Norman knights who received an Irish title, that of Earl of Ulster, from an English sovereign. He was a man of extraordinary stature and great courage. His son was created baron of Kingsale, Courcey, and Ringrone, titles maintained and descended in the family to the present 32nd baron. The de Courceys had castles at Duncearna, near the Old Head of Kinsale, and at Ringrone, opposite the town of Kinsale; they also built Kilbrittain castle, afterwards in the possession of the MacCarthys-Reagh. Duncearna is said to be the site of a dun, or residence, of the ancient kings of Munster.

The 1659 census did not enumerate by household. However, surname frequencies were noted. Below is a list of the surnames found in Courceys, in descending order of frequency.