Sophia Dobson Collet (1 February 1822 – 27 March 1894) was a 19th-century English feminist freethinker.

[1] She was described by Richard Garnett in the biography of William Johnson Fox as having attacks of a "disabling illness".

She was the aunt of social reformer Clara Collet (1860–1948), who worked with Charles Booth on his great investigative work Life and Labour of the People of London; and of Sir Wilfred Collet, governor of British Honduras and British Guiana.

"[6] She joined the Moral Reform Union, wrote articles on women's education and supported William Thomas Stead during his imprisonment in 1885.

[8] Her efforts to help Josephine Butler repeal the Contagious Diseases Acts in India put a strain on her relationship with Richard Holt Hutton of The Spectator.