John Joseph "Jack" Dunn (October 6, 1872 – October 22, 1928) was an American Major League Baseball pitcher at the turn of the 20th century. He later went on to become a minor league baseball club owner. In 1907, he took over management of the Baltimore Orioles, and bought the team the following year. He scouted and developed his own players. Arguably his most famous player was Babe Ruth, who quickly became the Orioles star player. However, due to financial pressures created by cross-town Federal League rival, the Baltimore Terrapins, Dunn moved the team to Richmond in 1914, and sold off Ruth. Ruth went on to major league stardom.
Dunn returned to Baltimore in 1916, and ran the team until his death in 1928.