MacFirbis (Irish: Mac Fhirbhisigh), also known as Forbes, was the surname of a family of Irish hereditary historians based for much of their known history at Lecan, Tireragh (now Lackan, Kilglass parish, County Sligo).
), said to be one of the last pagan Kings of Connacht, and were thus one of the many families who sprang from the Uí Fiachrach dynasty.
While this was their main function, they also appear to have served as poets and brehons to their patrons, possibly even musicians.
In the late medieval era the most well known was Giolla Íosa Mór Mac Fhirbhisigh fl.
was noted as well-travelled in Scotland, showing how far afield members of the clan would venture in practising their art.