William (III) de Beauchamp
William (III) de Beauchamp (c. 1215 – 1269) was an English baron and hereditary sheriff.
He married Isabel de Mauduit, who was the daughter of William de Mauduit, Baron of Hanslope and the sister of William Mauduit, 8th Earl of Warwick. They had eight children, of which his heir was his son, also named William de Beauchamp, who inherited the title of Earl of Warwick from his maternal uncle.
- Sudeley. "Sudeley family", Oxford Dictionary of National Biography, 23 September 2004. Accessed 13 January 2019.
- Sir Bernard Burke, C.B. LL.D., A Genealogical History of the Dormant, Abeyant, Forfeited, and Extinct Peerages of the British Empire, new edition (1883; reprint, Baltimore, Maryland: Genealogical Publishing Company, 1978), page 399. Hereinafter cited as Burkes Extinct Peerage.
- Dugdale, William (1655). Monasticon Anglicanum, Vol. 1, p. 571.