Gaddis is a surname. Notable people with the surname include:
C. J. Gaddis (born 1985), footballer
Christian Gaddis (born 1984), footballer
Gadabout Gaddis (1896-1986), television fisherman
John Lewis Gaddis (born 1939), historian of the Cold War and grand strategy
Miranda Gaddis, American crime victim
Thomas E. Gaddis (1908–1984), American author
Vincent Gaddis, American author
William Gaddis (1922-1998), American novelist