Diana Margaret Maddock, Baroness Maddock, Lady Beith (19 May 1945 – 26 June 2020) was a British Liberal Democrat politician. She was born in Berwick-upon-Tweed, Northumberland. Between 1993 to 1997, she was a Member of Parliament for Christchurch. In 1997, Maddock became a Lord Temporal. From 1999 to 2000, she was President of the Liberal Democrats.