John Howard "Fat Jack" Fisher (born March 4, 1939) is an American retired professional baseball player.

He played in Major League Baseball as a right-handed pitcher from 1959 through 1969 for the Baltimore Orioles, San Francisco Giants, New York Mets, Chicago White Sox and the Cincinnati Reds.

From August 24 to September 14 he pitched 29.2 consecutive scoreless innings and ended the year with a 3.41 earned run average, one of his lowest.

He was traded along with Billy Hoeft and Jimmie Coker from the Orioles to the Giants for Stu Miller, John Orsino and Mike McCormick on December 15, 1962.

In 1967, however, Fisher pitched the lowest-hit complete game of his career, a two-hit shutout over the Philadelphia Phillies (June 21 at Connie Mack Stadium).

"[7] In an eleven-season major league career, Fisher posted an 86–139 record with 1,017 strikeouts and a 4.06 ERA in 1,975.2 innings pitched, including 9 shutouts and 62 complete games.

Following his retirement from baseball, Fisher settled in Easton, Pennsylvania, where he lives five blocks from former world heavyweight boxing champion Larry Holmes.