Mary Reid Macarthur (13 August 1880 – 1 January 1921) was a British suffragist and Scottish trades unionist.
She was the general secretary of the Women's Trade Union League and was involved in the formation of the National Federation of Women Workers and National Anti-Sweating League.
In 1910 Mary led the women chain makers of Cradley Heath to victory in their fight for a minimum wage and led a strike to force employers to implement the rise.