The Sad Sack is an American fictional comic strip and comic book character created by Sgt. George Baker during World War II. Set in the United States Army, Sad Sack depicted an otherwise unnamed, lowly private experiencing some of the absurdities and humiliations of military life.

The term has come to signify a meek, inept, nonmilitary serviceman who means well but blunders his way, consistently in trouble, resignedly finding the odds always against him in military life. More broadly, it is applied to a hopelessly clumsy, incompetent or inept person, or a ludicrous misfit, also called an “eight ball”.