Mary Harris "Mother" Jones (August 1, 1837 – November 30, 1930), born in Cork, Ireland, was a prominent American labor and community organizer, a Wobbly, and a Socialist.

She was born Mary Harris, the daughter of a Roman Catholic tenant farmer, Richard Harris and his wife Ellen Cotter, on the northside of Cork city, Ireland. Some recent materials list her birthday as August 1, 1837, although she claimed her birthdate to be May 1, 1830. Her claims to an earlier date may have been an appeal to her grandmotherly image. The date of May 1 was chosen symbolically, representing the national labor holiday and anniversary of the Haymarket Riot.

The family emigrated to the United States and settled in the town of Monroe, Michigan. Harris studied and qualified to become a teacher in Toronto in 1857. She moved to Memphis, Tennessee in 1862 where she married George Jones, a member of the Iron Workers' Union. Two turning points in her life were the 1867 deaths of her husband and their four children (all under the age of five) during a yellow fever epidemic in Tennessee, and the 1871 Great Chicago Fire. After the death of her family, she moved to Chicago and recreated herself as an independent dressmaker. She lost her hard-earned home, shop and possessions in the Great Fire. This second loss catalyzed an even more fundamental transformation: she turned to the nascent labor movement and joined the Knights of Labor, a predecessor to the Industrial Workers of the World (IWW or "Wobblies"). As another source of her transformation into a radical organizer, biographer Elliott Gorn draws out her early Roman Catholic connection – including bringing to light her relationship to her estranged brother, Father William Richard Harris, Roman Catholic teacher, writer, pastor, and dean of Toronto's diocese of St. Catherine's, who was "among the best-known clerics in Ontario." Active as an organizer and educator in strikes throughout the country at the time, she was particularly involved with the United Mine Workers (UMW) and the Socialist Party of America. As a union organizer, she gained prominence for organizing the wives and children of striking workers in demonstrations on their behalf. She became known as "the most dangerous woman in America," a phrase coined by a West Virginia District Attorney Reese Blizzard in 1902, at her trial for ignoring an injunction banning meetings by striking miners. "There sits the most dangerous woman in America", announced Blizzard. "She crooks her finger—twenty thousand contented men lay down."