Evelyn Beatrice Hall
The Friends of Voltaire, written as S. G. Tallentyre, 1906
Hall was a biographer. Her summary became so well known that people started treating it as Voltaire's own.
the myth (Voltaire): Hall wrote the sentence to sum up Voltaire's attitude, not to quote him, and said so later. Voltaire never wrote these words, though the sentiment fits him.
Source: Wikiquote