Rory MacDermot

Prince of Coolavin was a title first applied by popular usage to Charles MacDermot, 1707–1758, then head of the MacDermot family of Moylurg. Up to the late 16th century the head of the family were still Kings of Moylurg, but had lost their lands due to confiscation.

The adoption of the term indicated that the family considered themselves Princes, and were in fact considered as such by their neighbours and kinsfolk. The title has continued to be used by the head of the family to denote their royal heritage, the current incumbent being Rory MacDermot, ninth of the MacDermots to be so styled.

The Prince of Coolavin

...
Wikipedia