Mary Irene Parlby was a Canadian women's farm leader, activist and politician. She served as MLA in the United Farmers of Alberta government from 1921 to 1935, serving as Minister without portfolio in the Cabinet of Alberta during that time. She worked to implement social reforms that helped farm women and children and was an advocate of public health programs. As a member of the Famous Five, she was one of five women who took the Persons Case first to the Supreme Court of Canada, and then to the British Judicial Committee of the Privy Council for the right of women to serve in the Senate of Canada. From 1930 to 1934, she was one of three Canadian representatives at the League of Nations in Geneva, Switzerland.

The Famous Five, also known as The Valiant Five, and initially as The Alberta Five, were five prominent Canadian suffragists who advocated for women and children: Henrietta Muir Edwards, Nellie McClung, Louise McKinney, Emily Murphy, and Irene Parlby. On August 27, 1927, they petitioned the federal government to refer the issue of the eligibility of women to be senator to the Supreme Court of Canada. This petition was the foundation of the Persons Case, a leading constitutional decision. Although most Canadian women had the vote in federal elections and all provinces but Quebec by 1927, the case was part of a larger drive for political equality. This was the first step towards equality for women in Canada and was the start to the first wave of feminism.