William Watson, Baron Thankerton, PC (8 December 1873 – 13 June 1948), was a Scottish Unionist Party politician and judge. Born in Edinburgh, Watson was the third son of Margaret Bannatyne (1846–1898) and William Watson, Baron Watson (1827–1899). He was educated at Winchester College and Jesus College, Cambridge, graduating with a Third in Law in 1895. In 1899, he was admitted to the Faculty of Advocates, taking silk in 1914. He was Procurator to the General Assembly of the Church of Scotland from 1918 to 1922, and was an advocate depute in 1919.