The O’Collins Clan is an ancient Irish clan descended from the Uí Fidgenti, a powerful dynasty in early medieval Munster, primarily based in the area of what is now County Limerick, Ireland. O’Collins is a genuinely indigenous Irish name. The name comes from the Anglicization of O’Coilean (the term Coilleain meaning ‘young hound, a young fearless warrior’ in the original tongue). For centuries the O’Collins Clan were part of the broader network of Gaelic nobility that shaped the social, political, and cultural landscape of medieval Ireland. The O’Collins were part of the extensive kinship networks among the Gaelic aristocracy in Munster. In addition to being closely allied with and related to other families descended from the Uí Fidgenti, such as the O’Donovans, they also maintained connections with the Eóganachta kings of Munster and other powerful dynasties, which was essential for their political alliances, clan survival and social status. The O’Collins clan controlled the territory around the Maigue River in County Limerick as Petty Kings of Upper Connello and Lords of Eighter Conghalach (Lower Connello) intermittently from the 9th to the 12th century. Like many Gaelic families, the O’Collins experienced shifts in power and territory due to conflicts with neighboring dynasties, Norse incursions, and later, the Norman invasions in the 12th century. In 1228 many of the “war loving O’Collins” were driven southward by the Normans into West Cork near the territory possessed by their kinsmen Cathal, son of Crom O’Donovan. Others left for Donegal. Some of the remaining members in Limerick retained power in Claonglass until about the beginning of the 14th century when their power also passed to the FitzGeralds. In 1266, Mahon O’Collins, lord of Claonglass, and the last of the ruling O’Collins, was killed by his wife, with a thrust of a knife, in a fit of jealousy. This was the end of the Clan O’Collins as a clan. This book is the history of the O’Collins Clan from the time they split from the rest of the Ui Fidgenti in 950AD, until the Clan was destroyed by the invading Norman family, the FitzGeralds, and then continue tracing members of the Collins Clan to the 21st century Though there are many people named Collins descended from the O’Collins Clan who are scattered around the world, only one Collins family line appears to have documentation that demonstrates a direct descent from the O’Collins Clan nobility. We present that family in this book. Many historians have noted that history is not a simple line of linear events where one thing leads to another that leads to another. It is much more complicated than that. In this history there will be kings, sub kings, overkings, high kings, not to mention intermarried clans, chiefs, chieftains, Normans and Vikings. All shifting alliances and loyalties. If there was ever an example of a matrix of history this is surely it.