Peter Francis Walter Kerr, 12th Marquess of Lothian, KCVO (8 September 1922 – 11 October 2004) was a British peer, politician and landowner.

He was educated at Ampleforth College and Christ Church, Oxford, and joined the Scots Guards.

He returned to the Foreign Office with Alec Douglas-Home (then formerly Lord Home) in 1970, serving as parliamentary under-secretary for two years.

He was also a member of the Royal Company of Archers, commandant of the Special Constabulary in the Scottish Borders, and a Knight of Malta.

They had five children: His elder son, the Conservative politician Michael Ancram, succeeded to the marquessate on his death.