John Emil Jaha (born May 27, 1966) is a former first baseman in Major League Baseball who had a 10-year career from 1992 to 2001. He played for the Milwaukee Brewers and Oakland Athletics, playing in both the American League and National League. He was elected to the American League All-Star team in 1999.
After an injury-plagued Major League career with the Brewers, Jaha signed a minor-league contract with the Oakland Athletics in 1999. Although Jaha wasn't expected to make the team - in fact, he was left out of the team's media guide that spring - he turned in a remarkable comeback season. Earning his first All-Star berth along the way, he finished the season with 35 home runs (tying Dave Kingman for most by an Oakland designated hitter) and 111 RBIs and was named the American League Comeback Player of the Year.