Grantham is an English surname which has been spread to North America and Australasia. Notable people with the surname include:
Alexander Grantham (1899–1978), British colonial administrator
Donald Grantham, American composer
Sir Guy Grantham, (1900–92) British Admiral, Commander-in-Chief at Portsmouth
Jeremy Grantham, Chairman of the Board of Grantham Mayo Van Otterloo, a Boston-based asset management firm
Joseph Grantham (died 1830), first police officer to be killed on duty in the United Kingdom
Leslie Grantham, British TV actor
Roy Grantham (1926–2013), British trade union leader
Sir Thomas Grantham, commander of the naval fleet of the British East India Company
William Grantham (1835–1911), English judge and Conservative M.P. for East Surrey and Croydon
