Helen Joy Davidman (April 18, 1915 – July 13, 1960), also known as Joy Gresham, was an American poet and writer, a radical communist, and an atheist until her conversion to Christianity in the late 1940s. Her first husband was the writer William Lindsay Gresham (a divorcé). They had two children together: David and Douglas. Her second marriage was to the writer and Oxford don, C. S. Lewis.