O'Neill of Clanaboy was a prominent Irish noble family that emerged in the 12th century. They were part of the larger O'Neill dynasty, which played a significant role in the history of Ulster. The Clanaboy branch was known for its influence in the eastern part of Ireland, particularly in the area around County Down. The family was involved in various conflicts and power struggles, especially during the Tudor conquest of Ireland. They were recognized for their leadership and military prowess, often opposing English rule. The O'Neill of Clanaboy lineage eventually declined, but their legacy remains an important part of Irish history.