Alastair John Morrison, 3rd Baron Margadale DL (born 4 April 1958) is a British peer.
Margadale is the son of James Morrison, 2nd Baron Margadale and Clare Barclay. He married, firstly, Lady Sophia Cavendish, daughter of Andrew Cavendish, 11th Duke of Devonshire and The Honourable Deborah Mitford, on 19 July 1988. They had two children:
He married, secondly, Amanda Fuller, daughter of Michael Fuller, on 2 September 1999. He succeeded his father in the barony on 6 April 2003 and the same year was appointed a Deputy Lieutenant for Wiltshire.