Mary Doreen Archer, Baroness Archer of Weston-super-Mare (born Mary Doreen Weeden,on 2nd January 1948) is a British scientist specialising in solar power conversion. She studied physical chemistry at Imperial College, London, and then became a lecturer at Cambridge University. From 1988 to 2000 she was Chairman of the National Energy Foundation , which promotes renewable energy. In 2002 she was appointed Chairman of Addenbrooke's NHS Trust, Cambridge.

Archer is better known to the general public as the wife of the novelist and former politician Jeffrey Archer, whom she married in 1966. When he was granted a life peerage in 1992, she gained the title The Lady Archer of Weston-super-Mare. In 1987 she gave evidence at the High Court in a libel case brought by her husband against the Daily Star newspaper, and in 2001, when Lord Archer of Weston-super-Mare was accused of perjury in that trial, she appeared at the Old Bailey to defend him. It is often claimed that Mary Archer is substantially responsible for her husband's popular novels.

She has two children, William Harold Archer (born 1972) and James Howard Archer (born 1974).