William (III) de Beauchamp

William (III) de Beauchamp (c. 1215 – 1269) was an English nobleman and feudal baron, holding the title of Baron of Elmley. He was the son of William (II) de Beauchamp and Isabel Mauduit. He inherited the barony of Elmley upon his father's death in 1236.

William de Beauchamp was a prominent figure during the reign of King Henry III, and he played a significant role in the political and military events of the period. He was a supporter of the King during the Second Barons' War, siding against Simon de Montfort. He participated in several key battles and sieges.

He married Isabel de Clare, daughter of Gilbert de Clare, 4th Earl of Hertford, and Isabel Marshal. Through this marriage, the Beauchamp family was connected to some of the most powerful families in England. William and Isabel had several children, including William (IV) de Beauchamp, who succeeded him as Baron of Elmley. William (III) de Beauchamp died in 1269 and was succeeded by his son.