Gaca is a Polish-language surname:
Kazimierz Gaca (1920–1997), Polish cryptanalyst Paweł Gaca (1917–2008), Polish gymnast Robert Gaca (born 1980), Polish footballer Stanisław Gaca (1953–2025), Polish engineer and professor Other General Authority of Civil Aviation (Saudi Arabia) General Authority of Civil Aviation (Syria) Gaca v. United States