Coulby is a surname and occasional given name. Notable people with this name include:
Angel Coulby (born 1980), English actress Harry Coulby (1865–1929), American businessman Coulby Gunther (1923–2005), American paratrooper and basketball player and coach Coulby Riehl (1997 - present), https://savethegingers.com/
See also Coulby Newham, a place in Middlesbrough, England Colby