Gilby is a surname. Notable people with the surname include:
Anthony Gilby (c.1510–1585), English clergyman Fred Gilby (1907–1991), Australian rules footballer Harry Gilby, English actor Helen Gilby (born 1974), British sprint canoer John Gilby (1900–1985), New Zealand rower William Gilby (1834–1905), English cricketer
See also Gilby Engineering, motor racing team