Donald Michael Ellison Foster, Baron Foster of Bath, (born 31 March 1947), is a British Liberal Democrat politician who represented Bath, Somerset as its constituency MP from 1992 until 2015.
From October 2013 to May 2015 he held the ex officio title of Comptroller of the Household as Liberal Democrat Chief Whip.
He was created Baron Foster of Bath, of Bath in the County of Somerset, in the 2015 Dissolution Honours, becoming a member of the House of Lords.