A screwball is a baseball pitch that is thrown so as to break in the opposite direction of a slider or curveball. Depending on the pitcher's arm angle, the ball may also have a sinking action.

Carl Hubbell was one of the most renowned screwball pitchers in the history of Major League Baseball. Hubbell was known as the "scroogie king" for his mastery of the pitch and the frequency for which he threw it. Other famous screwball artists include Tug McGraw and Cy Young Award winners Mike Cuellar, Fernando Valenzuela and Mike Marshall.