A queen mother is a former queen, often a queen dowager, who is the mother of the reigning monarch. The term has been used in English since the early 1560s. It arises in hereditary monarchies in Europe and is also used to describe a number of similar yet distinct monarchical concepts in non-European cultures around the world. The rank does not go to all mothers of monarchs though. A mother of a ruling monarch may only be referred to as Queen Mother if she was a Queen Consort as opposed to a Princess Consort.

Elizabeth Angela Marguerite Bowes-Lyon was Queen of the United Kingdom and the Dominions of the British Commonwealth from 11 December 1936 to 6 February 1952 as the wife of King George VI. She was also the last Empress of India from 1936 until the British Raj was dissolved in August 1947. After her husband died, she was officially known as Queen Elizabeth The Queen Mother, to avoid confusion with her daughter Queen Elizabeth II.