Frank Victor Shellenback (December 16, 1898 – August 17, 1969) was an American pitcher, pitching coach, and scout in Major League Baseball.
As a pitcher, he was famous as an expert spitballer when the pitch was still legal in organized baseball; however, because Shellenback, then 21, was on a minor league roster when the spitball was outlawed after the 1919 season, he was banned from throwing the pitch in the Major Leagues.
As a result, Shellenback spent 19 years (1920–38) — the remainder of his active career — throwing the spitball legally in the Pacific Coast League.