Ethel Lilian Voynich was an Anglo-Irish novelist and musician, born as Ethel Lilian Boole on 11 May 1864 in Cork, Ireland. She was a supporter of several revolutionary causes and grew up in Lancashire, England.

Voynich was a significant figure on the late Victorian literary scene and within Russian émigré circles. She is best known for her novel The Gadfly, which became hugely popular during her lifetime, especially in the Soviet Union.

She was the daughter of the famous mathematician George Boole and feminist philosopher Mary Everest, who was the niece of George Everest. In 1893, she married Wilfrid Michael Voynich, a revolutionary, antiquarian, and bibliophile, known for the Voynich manuscript.