Gwen John (1876-1939) was a Welsh artist.

She was born in Haverfordwest, Wales. Like her brother, Augustus John, Gwen studied at the Slade School of Art (1895-98). She worked briefly in Paris with James Whistler and began to exhibit her work in London in 1899. In 1906, she began modelling for the sculptor Auguste Rodin in Paris, where she then lived, and became his mistress.

Most of her artwork in later life was small-scale portraits and still-lifes. Although overshadowed by her popular brother, many would now say (as Augustus did) that Gwen was the more talented of the two, although she did not receive the same recognition.