Sir John Warcup 'Kappa' Cornforth, AC, CBE, FRS (born 7 September 1917), is an Australian scientist who won the Nobel Prize in Chemistry in 1975 for his work on the stereochemistry of enzyme-catalyzed reactions.

His mother, Hilda Eipper (1887–1969), was the granddaughter of Christopher Eipper.
He studied organic chemistry in the School of Chemistry at the University of Sydney and graduated with first-class honours and the University medal in 1937.
He was knighted in 1977. He was awarded the Corday-Morgan medal in 1953, Royal Medal in 1976 and the Copley Medal in 1982.
He is a member of the Royal Society and is still very active in chemistry research at the University of Sussex.