John Arthur Pregenzer (born August 2, 1932) is an American former professional baseball pitcher who appeared in parts of two Major League Baseball seasons (1963–64) for the San Francisco Giants. The right-hander stood 6 feet 5 inches (1.96 m) tall and weighed 220 pounds (100 kg). In Pregenzer's 19 games for the Giants, he went undefeated in two decisions. In 27⅔ innings pitched, he allowed 29 hits and 19 bases on balls. He recorded 13 strikeouts and one save. He was a successful minor league pitcher; over eight campaigns, he won 66 games, losing 49 with an earned run average of 3.67.