McDermott or MacDermott is an Irish surname and the anglicised version of Mac Diarmada (also spelled Mac Diarmata), the surname of the ruling dynasty of Moylurg, a kingdom that existed in Connacht from the 10th to 16th centuries.
The last ruling king was Tadhg mac Diarmata, who ruled until 1585.
As a modern day surname, McDermott is mostly found in western Ireland and County Roscommon.
Some notable people with the surname are listed below.