William Phillimore Watts Phillimore (formerly Stiff) MA BCL (27 October 1853 – 9 April 1913) was an English solicitor, genealogist and publisher.

William Phillimore Watts Stiff was born on 27 October 1853 in Nottingham, the eldest son of Dr William Phillimore Stiff M.B. Lond., M.R.C.S. Eng., of Sneinton, Nottingham, afterwards superintendent of Nottingham General Lunatic Asylum, and Mary Elizabeth, daughter of Benjamin Watts of Bridgen Hall, Bridgnorth, Shropshire. In 1873 William Stiff senior changed the family surname by royal licence to Phillimore, his great-grandmother's maiden name.^[1] William junior studied at The Queen's College, Oxford, and was awarded a second-class degree in Jurisprudence in 1876.^[2]

Phillimore was a solicitor. In 1897 he founded the publishing business which bears his name. From 1888 onwards, he advocated the formation of local record offices, and to that end prepared bills to be put before Parliament.

Phillimore initiated the foundation of several record publication societies: the Index Library (afterwards the germ of the British Record Society) in 1887; the Scottish Record Series (afterwards Scottish Record Society) in 1896; the Thoroton Society of Nottinghamshire in 1897; the Canterbury and York Society in 1904, publishers of English medieval ecclesiastical records; and the Irish Record Society in 1909. He was a corresponding member of the New England Historic Genealogical Society, the Virginia Historical Society, and the Chicago Historical Society.

Phillimore married Jane Graham in 1887 and they left one surviving son, Wilfred Henderson Phillimore.

Phillimore died on 9 April 1913 in Torquay, Devon.

The publishing house he founded, Phillimore & Co., later based in Chichester, West Sussex, became a prominent publisher in the fields of local history and family history, and survives as an imprint of The History Press.

• Tiller, Kate (2004). "Phillimore [formerly Stiff], William Phillimore Watts (1853–1913)". Oxford Dictionary of National Biography (online ed.). Oxford University Press. doi:10.1093/ref:odnb/57556. (Subscription or UK public library membership required.)
• Who Was Who, 1897–1916 A & C Black Ltd, 1920
• The Genealogist, vol. 30 (October 1913)