Helen Gregory MacGill (née, Gregory; after first marriage, Flesher; after second marriage, MacGill; January 7, 1864 – February 27, 1947) was one of Canada's first woman judges - and for many years the country's only woman judge - journalist, and a noted women's rights advocate in Canada, where she fought for female suffrage. Daughter of Emma and Silas Ebenezer Gregory, her maternal grandfather was Upper Canada barrister and judge Miles O'Reilly, noted for his successful defense of the group accused of participating in the 1837 Upper Canada Rebellion.