William Martin, 1st Baron Martin (died 1324), Lord of Cemais and Barnstaple was an English noble. He fought in the wars in Wales, Gascony, Flanders and Scotland. He was a signatory of the Baron's Letter to Pope Boniface VIII in 1301.

William was the eldest son of Nicholas Martin and Maud de Brain.^[1] He served in Wales, Gascony, Flanders in 1297 and in Scotland. William took part in the battle of Falkirk on 22 July 1298. He was a signatory of the Baron's Letter to Pope Boniface VIII in 1301.

He died in 1324 and was succeeded by his second son William. His eldest son Edmund pre-deceased him.

William married firstly Eleanor, the widow of John de Mohun, she was a daughter of Reginald FitzPeter and Alice. They had the following children:

• Edmund Martin d.s.p married Margaret Hastings.
• William Martin d.s.p married Joan Hastings.
• Eleanor Martin married Philip Colombers^[2] of Nether Stowey on and heir to John de Columbers and Alice, daughter and co-heiress of Stephen de Penshurst and William de Hastings son of John_Hastings,_1st_Baron_Hastings and Isabel de Valence.
• Joan Martin married Henry de Lacy, Earl of Lincoln and Nicholas d'Audley 1st Lord Audley.

William married secondly Amicia, widow of Henry de Pomeroy, she was a daughter of Geoffrey de Camville.

The Martin line ceased to exist after the death of Edmund and William, Eleanor died without issue, and the titles revered to the heirs of Joan Martin. ^[3][4]

• Cokayne, George Edward. The Complete Peerage of England, Scotland, Ireland, Great Britain, and the United Kingdom, Vol. V (1893).