John Cass (1661–1718) was a British merchant and politician.
Sir John Cass may also refer to:
Sir John Cass's Foundation, an education charity in London Cass Business School, the former name of The Business School at City, University of London Sir John Cass (19th century), merchant and father of Annie Pearson, Viscountess Cowdray John Cass (1813–1889), master mariner and Captain of the Caduceus
See also John Kass, American columnist