Theresa Thornycroft (1853 – July 1947) was an English sculptor and painter. She was a member of the inventive and artistic branch of the Thornycroft family. Her father was the sculptor and engineer Thomas Thornycroft (1815–1885), and her mother, the sculptor Mary Francis (1814–1895), worked under both her maiden name and her married name. She exhibited her paintings at the Royal Academy of Arts in London before she turned twenty-two. She married Alfred Ezra Sassoon (1861–1895) of the Jewish Sassoon family. Because she was Anglo-Catholic, he was disinherited by the Sassoon family for marrying her. They had three sons: Michael Thornycroft Sassoon (1884–1969), Siegfried Sassoon (1886–1967), and Hamo Watts Sassoon (1887–1915).