William Devereux, Baron Devereux of Lyonshall (c. 1244–1314) was an English noble who was an important Marcher Lord as he held Lyonshall Castle controlling a strategically vital approach to the border of Wales in the time of Edward I and Edward II. He was the first of this family officially called to Parliament, and was ancestor to John Devereux, 1st Baron Devereux of Whitchurch Maund, the Devereux Earls of Essex, and the Devereux Viscounts of Hereford. His coat of arms was the same as his father's and described as "argent, fess and three roundels in chief gules" which passed to the descendants of his first wife, the Devereux of Bodenham; or "gules od un fesse d'argent ove turteaus d'argent en le chief" which passed to the descendants of his second wife, the Devereux of Frome.