John William Mellor PC DL QC (26 July 1835 – 13 October 1911) was an English lawyer and Liberal Party politician. Born in London, the eldest of the eight sons of Rt Hon. Sir John Mellor, of Otterhead, Devonshire, a Judge of the Queen's Bench Division of the High Court, Mellor was educated at Trinity Hall, Cambridge. In 1860 he married Caroline Paget, daughter of Charles Paget, MP. He was appointed a Privy Counsellor in 1886.