Mary Manson Dreaver (née Bain, 31 March 1887 – 19 July 1961) was a New Zealand politician of the Labour Party.
She was born in Dunedin, the oldest of 13 children of Alexander Manson Bain and Hanna Kiely. She married Andrew James Dreaver in 1911. She was a minister and president of the National Spiritualist Church of New Zealand, a journalist as Maorilander in the New Zealand Woman's Weekly, and a broadcaster on Radio 1ZB as Aunt Maisy. In 1934 she became the first woman minister appointed by the church in New Zealand.
Dreaver sought selection by the Labour Party for the 1930 by-election in the Parnell electorate, but was beaten by Thomas Bloodworth.
In 1931 she was elected to the Auckland Hospital Board as a Labour candidate. In 1933 a visit by her to the hospital kitchen and claims of long hours and "sweated labour" there aroused controversy on the board.
In the 1938 election she stood for Labour in Remuera, coming second.
In 1941 she won the Waitemata electorate when a by-election was held after the death of the previous Labour Party MP, Jack Lyon. She was defeated in the next (1943) general election, by the National Party candidate, Henry Thorne Morton.
She was the third woman to be elected to Parliament after Elizabeth McCombs and Catherine Stewart. She also was on several Auckland local bodies.
Dreaver and Mary Anderson were the first two women appointed to the Legislative Council. They were appointed by the First Labour Government in 1946 (after a law change in 1941 to make women eligible); and they served to 1950 when the Legislative Council was abolished.
In the 1946 New Year Honours, Dreaver was appointed a Member of the Order of the British Empire for services in connection with recruiting for the Women's Land Army.
She died in Auckland on 19 July 1961. She was survived by her husband (by only three months), three daughters and two sons.