Many Old Granthamians have made their mark in the world in the 480 years since the school was founded. Here is a list of the better known:

 William Cecil, Lord Burghley

'Cambridge Platonist', Henry More

Poet Laureate Colley Cibber

Sir Isaac Newton 18th century mathematician,

John Newcombe

World War I fighter ace Albert Ball VC DSO and MC two bars (1896-1917)

Joseph Harcourt Tombs, VC (1884-28 June 1966), a Lance-Corporal in the 1st Battalion, King's Regiment (Liverpool), British Army during the First World War

John W C Wand, Archbishop of Brisbane from 1934 to 1943 and Bishop of London from 1945 to 1956

Norman Shrapnel (1912-2004) chief fiction reviewer for the The Guardian

Noel F Cox OBE, Warden of the Royal Academy of Music

George M H Walker, editor, publisher and engineer

Oliver Anderson, writer

Andy Bond, president and CEO of Asda

Jamie Winter, footballer

Jason Haynes, cricketer, left-handed opening batsman, captained Barbados in 2008