Clementina Maria Black (27 July 1853 – 19 December 1922) was an English writer, feminist and pioneering trade unionist, closely connected with Marxist and Fabian socialists.

[3] She and her sisters moved in the 1880s to Fitzroy Square in London, where she spent her time studying social problems, doing literary work, and lecturing on 18th-century literature.

Black made the acquaintance of Marxist and Fabian socialists, such as Olive Shreiner, Dollie Radford, and Richard Garnett of the British Museum.

[5] In 1896 she began to campaign for a legal minimum wage as part of the Consumers League and credited as being involved in the Bryant & May match company industrial dispute[6] where exploited women workers eventually took action.

By 1912–1913, Black was acting editor of The Common Cause[7] the "organ of the women's movement for reform", using her writing rather than direct action (unlike the militant suffragettes) to influence change.

She took into her home her niece Gertrude Speedwell, after the girl's father, Clementina's brother Arthur, had murdered his wife and son, then committed suicide.