William de Grandison, 1st Baron Grandison
William de Grandison (died 1335), was an English noble, and Deputy Justiciar of North Wales.
William was a younger son of Pierre de Grandison and Agnes Neufchâtel. He was the younger brother of a key ally and envoy, for King Edward I of England, Otto de Grandson, Grandison being an anglicisation of Grandson.
He served in the household of Edmund, Earl of Lancaster. He was active in the wars in Gascony and Scotland. During 1292, he was granted a license to crenellate his manor of Ashperton, Herefordshire.