Cathy de Monchaux (born 1960) is a British sculptor.

de Monchaux was born in London. She studied first at the Camberwell School of Art, and later at Goldsmiths College in London. Her sculptures use materials such as glass, paper, metal and leather. They frequently juxtapose seductive soft elements, often with strongly sexual overtones, with harder materials, often spikey or in some way appearing to constrain the softer parts, resulting in work which is both sensual and threatening.

de Monchaux's work from the early 1990s often achieves this effect by the combination of red velvet and steel in simple and strong constructions, but later works have tended to move towards lighter colours, and a more ornamental approach.

de Monchaux was shortlisted for the Turner Prize in 1998. She currently lives in London and is a part-time teacher at the Slade School of Art. However, she has exhibited in the United States almost as much, if not more, as she has in England.