Kelvin John Lancaster (10 December 1924 – 23 July 1999) was an Australian mathematical economist and John Bates Clark professor of economics at Columbia University. He is best known for the development of the Theory of the Second Best with Richard Lipsey. Lancaster was also active in developing the calculus of qualitative economics, formulating the household production function, and applying the hedonic model to the estimation of housing prices. Lancaster attended Sydney Boys High School, graduating in 1940.