Evelyn Beatrice Hall, (1868 - 1919), who wrote under the pseudonym S.G. Tallentyre, was a writer best known for her biography of Voltaire. She completed her biography of Voltaire The Friends of Voltaire in 1906. She wrote the phrase, which is often mis-attributed to Voltaire, "I disapprove of what you say, but I will defend to the death your right to say it," as an illustration of Voltaire's beliefs.[1]

http://en.wikipedia.org/wiki/Evelyn_Beatrice_Hall