Robert Adam Ross Maclennan, Baron Maclennan of Rogart (26 June 1936 – 18 January 2020) was a British politician and life peer. He was the last leader of the Social Democratic Party (SDP) from 1987 to 1988. He was the president of the Liberal Democrats from 1995 to 1998. He served as a Member of Parliament (MP) from 1966 to 2001, when he was raised to the House of Lords.