Murchadh (or Muircheartach) Riabhach Ó Cuindlis (fl. 1398–1411) was an Irish scribe of the Ó Cuindlis family of brehons and scholars. He was said to be a native of Bally Lough Deacker in what is now the extreme south of County Galway. Ó Cuindlis was one of the scribes of the Book of Lecan under the guidance of Giolla Íosa Mor mac Donnchadh MacFhirbhisigh; and later a scribe of An Leabhar Breac at Duniry.