Phelim Reagh MacDavitt or Phelim Reagh MacDevitt (Irish: Feidhlimidh Riabhach Mac Dhaibheid, or Brindled Felim - probably a reference to a white streak or streaks in his hair) was a Gaelic Irish warrior and landowner notable for his participation in the Nine Years War and later in O'Doherty's Rebellion in 1608.

They now rescued Cahir from captivity and had him proclaimed as Chief of the Name of Clan O'Doherty and Lord of Inishowen by Henry Docwra, English governor of Derry.

Both Cahir O'Doherty and Phelim Reagh had problems with local government officials in the years after the war, once the more friendly Docwra had been replaced, and both felt they were being pushed into rebellion by their treatment.

He was on hand when the city's Governor George Paulet (who was intensely disliked by both Protestant planters and local Gaels) was killed.

He was taken to Lifford, found guilty of high treason by a civilian court, and sentenced to be hanged, drawn and quartered.