This name comes from Muiredach Mullethan, who was King of Connacht from 697 to 702. The name is spelled in different ways: McDermott-Roe. MacDermot, and Dermody, while in the United States it's Kermode. The area around Lough Key in County Roscommon used to be a MacDermot stronghold. The Cistercian abbey at nearby Boyle was also under the patronage of the MacDermots and no fewer than thir-teen heads of this family are buried there.
A famous legend is connected with Lough Key. Una Bhan MacDermot and Thomas Laidir McCostello were ill-fated lovers from rival families. Una's family confined her to Castle Island, where she became ill and died. McCostello swam out to her grave every night until he too, died. The two lovers were buried together, and two rose-trees over their graves became entwined. Those trees are still there today.
The MacDermots are the only family in Ireland to have added the courtesy title of Prince to their name. The current head of the principal branch of the family is Niall MacDermot, Prince of Coolavin.