Constance Clara Garnett (née Black; 19 December 1861 – 17 December 1946) was an English translator of nineteenth-century Russian literature. She was the first English translator to render numerous volumes of Anton Chekhov's work into English and the first to translate almost all of Fyodor Dostoevsky's fiction into English. She also rendered works by Ivan Turgenev, Leo Tolstoy, Nikolai Gogol, Ivan Goncharov, Alexander Ostrovsky, and Alexander Herzen into English. Altogether, she translated 71 volumes of Russian literature, many of which are still in print today.

Garnett was born in Brighton, England, the sixth of the eight children of the solicitor David Black (1817–1892), afterwards town clerk and coroner, and his wife, Clara Maria Patten (1825–1875), daughter of painter George Patten. Her brother was the mathematician Arthur Black, and her sister was the labor organizer and novelist Clementina Black. Her father became paralyzed in 1873, and two years later her mother died from a heart attack after lifting him from his chair to his bed.

She was initially educated at Brighton and Hove High School. Afterwards she studied Latin and Greek at Newnham College, Cambridge, on a government scholarship. In 1883 she moved to London, where she started work as a governess, and then as the librarian at the People's Palace Library. Through her sister, Clementina, she met Dr. Richard Garnett, then the Keeper of Printed Materials at the British Museum, and his son Edward Garnett, whom she married in Brighton on 31 August 1889. Edward, after working as a publisher's reader for T. Fisher Unwin, William Heinemann, and Duckworth, went on to become a distinguished reader for the publisher Jonathan Cape. In the summer of 1891, then pregnant with her only child, she was introduced by Edward to the Russian exile Feliks Volkhovsky, who began teaching her Russian. He also introduced her to his fellow exile and colleague Sergius Stepniak and his wife Fanny. Soon after, Garnett began working with Stepniak, translating Russian works for publication; her first published translations were A Common Story by Ivan Goncharov, and The Kingdom of God is Within You by Leo Tolstoy. The latter was published while she was making her first trip to Russia in early 1894. After visits to Moscow and Saint Petersburg, she traveled to Yasnaya Polyana where she met Tolstoy; although the latter expressed interest in having her translate more of his religious works, she had already begun working on the novels of Turgenev and continued with that on her return home. Initially she worked with Stepniak on her translations; after his untimely death in 1895, Stepniak's wife Fanny worked with her. From 1906, her favorite amanuensis was a Russian girl, Natalie Duddington whom she had met in Russia and in whom she found "real intellectual companionship".

Over the next four decades, Garnett would produce English-language versions of dozens of volumes by Tolstoy, Gogol, Goncharov, Dostoyevsky, Turgenev, Ostrovsky, Herzen and Chekhov.

Her son and only child, David Garnett, trained as a biologist and later wrote novels, including the popular Lady into Fox (1922).

By the late 1920s, Garnett was frail and half-blind. She retired from translating after the publication in 1934 of Three Plays by Turgenev. After her husband's death in 1937, she became quite reclusive. She developed a heart condition, with attendant breathlessness, and in her last years had to walk with crutches. She died at The Cearne, Crockham Hill, Kent, at the age of 84.