Gadd is a surname. Notable people with the surname include:
Anthony Gadd (1917–1996), British bobsledder
Christianne Gadd, former name of actress Christianne Oliveira
Knut Gadd (1916–1995), Swedish water polo player
Paul Francis Gadd (born 1944), the real name of British glam rock singer and convicted paedophile Gary Glitter
Renee Gadd (1908–2003), Argentine-born British film actress
Stephen Gadd (born 1964), English operatic baritone
Steve Gadd (born 1945), American drummer
Trevor Gadd (born 1952), English athlete
Will Gadd, Canadian ice climber and paraglider pilot
Fictional characters:
Professor E. Gadd, fictional character