Castell is a surname of Catalan origin. Notable people with the surname include:
- Adela Castell (1864–1926), Uruguayan educator, writer and poet
- Alan Castell (born 1943), English cricketer
- David Castell, American record producer, musician and recording engineer
- Edmund Castell (1606–1685), English orientalist
- John Castell (aka John Castle), 15th-century Master of University College, Oxford and a Chancellor of the University
- Jordan Castell, American football player
- Lacksley Castell (1962–1984), Jamaican reggae singer
- Patricia Castell (1926–2013), Argentine actress
- Sir William Castell (born 1947), British businessman