Gast is a surname, and may refer to:
Alice Gast, academic and administrator
Camille du Gast, sportswoman and social pioneer
Eric Gast, record producer
John Gast, English trade unionist
John Gast, American professional baseball player
John Gast, Prussian-born painter
Leon Gast, American documentary filmmaker
Luce de Gast, 13th century lord
Margaret Gast, German-born American racing cyclist
Paul Werner Gast, geologist
Silke Gast, German javelin thrower
Wolfgang Gast, decorated Waffen-SS officer
Gast may also refer to
Gast gun, twin barreled machine gun
