Ancestor of the O'Briens of Ennistymon & Dough.

By some reckoning, he was King of Thomond from 1553-1558, when he was deposed, and again 1563-64 when he abdicated. However, by some reckoning, there was no King of Thomond after his uncle, Murrough.

From "A New History of Ireland," edited by Moody, Martin & Byrne, vol 3, ISBN 0-19-821739-0, 1976, p 88:
[Around 1567] South Connacht was in turmoil because of the succession dispute of the Man an Iarla half-brothers, Ulick and John, sons of Richard Sassanach, second earl of Clanricard. Thomond, where the earl was opposed by his uncle, was in like case. The original earls of Clanricard and Thomond had, unfortunately for the English, died shortly after their English ennoblement. The transition from pseudo-Gaelic or pure Gaelic rule to the English system was thus, in neither lordship, managed by a vigorous, able and long-lived appointee. In Clanricard, the promiscuous marital relations of the Burkes, together with a plenitude of offspring, added to the confusion. In both lordships, those who considered that Gaelic institutions were preferable, or gave them a better chance of furthering their own ends, resisted change.