William Baillie, Lord Polkemmet (1736-1816) was a Scottish law lord.
Baillie was the eldest son of Thomas Baillie of Polkemmet WS (died 1785), and Isabel Walker (died 1777). He was admitted advocate 1758, judge 1793, resigned 1811.
His Edinburgh address was 62 George Street.
He died 14 March 1816.
He married Margaret Culquhoun, daughter of Sir James Culquhoun of Luss in 1768. In 1803 he married again, to Janet Sinclair, sister of Sir John Sinclair, and a cousin to his first wife.
The Baillie baronets were descended from Lord Polkemmet.
"". Dictionary of National Biography. London: Smith, Elder & Co. 1885–1900.