William Watson, Baron Watson, PC (25 August 1827 – 14 September 1899)^[1][2] was a Scottish lawyer and Conservative Party politician. He was Lord Advocate, the most senior Law Officer in Scotland, from 1876 to 1880, and was then appointed a Lord of Appeal in Ordinary.

Watson was born in Covington, Lanarkshire on 25 August 1827. He was the eldest son and second of the six children of Eleonora and Reverend Thomas Watson. He was educated privately and studied law at the universities of Glasgow and Edinburgh.^[1] He was admitted to the Faculty of Advocates in 1851^[1] and appeared for the defence of Dr Edward William Pritchard, the poisoner, in 1865.^[3]

Watson was appointed Solicitor General for Scotland, one of the Scottish Law Officers and deputy to the Lord Advocate, in 1874,^[4] and was elected Dean of the Faculty of Advocates in 1875.^[1] In 1876, the Lord Advocate, Edward Gordon, was appointed a Lord of Appeal in Ordinary (Lord Gordon of Drumearn) and resigned as Lord Advocate and Member of Parliament (MP) for Glasgow and Aberdeen Universities. Watson won the ensuing by-election^[5] and was appointed Lord Advocate.^[6] He was appointed a Privy Counsellor in 1878.^[7]

Watson did not stand for re-election at the 1880 general election,^[5] and was instead appointed a Lord of Appeal in Ordinary^[8] as Baron Watson, of Thankerton in the County of Lanark.^[8] As a member of the Privy Council, he was also entitled to sit on the Judicial Committee of the Privy Council.

Watson married Margaret Bannatyne (1846-1898) in 1868, and the couple had five sons and a daughter. His son William also became a law lord as Lord Thankerton while another son, Ronald, was a first-class cricketer. Watson lived at 20 Queen's Gate in South Kensington, and was a member of the Athenæum and the Carlton Club.^[1]

He is buried in Dean Cemetery in Edinburgh against the north wall, of the Victorian north extension, near the north-west corner.