Frank Victor Shellenback
- Bats Right, Throws Right
- Height 6' 2", Weight 192 lb.
- School Santa Clara University
- High School Hollywood High School
- Debut May 8, 1918
- Final Game July 5, 1919
- Born December 16, 1898 in Joplin, MO USA
- Died August 17, 1969 in Newton, MA USA
Frank Shellenback holds the record for most wins in the Pacific Coast League, as well as the record for most wins in any single minor league, with 295. His career minor league record was 315-192. Shellenback was effectively trapped in the minor leagues because he depended on the spitball. He didn't make the list of legal spitballers in the majors because he was in the minor leagues at the time, but he did make the list for the PCL. That effectively trapped him in the PCL because he couldn't use his best pitch in any other league.
After his career, Shellenback was a long-time pitching coach for Leo Durocher. In 1943 Shellenback was elected to the Pacific Coast League Hall of Fame. Shellenback was the supervisor of minor league personnel for the New York and San Francisco Giants from 1956 to 1959, then scouted for the Giants from 1960 to 1969.
He was the first pro manager for Ted Williams.
He is the uncle of Jim Shellenback.
- Andrew Battifarano: "Shellenback shined during lengthy PCL career: Right-hander racked up records before spitball was banned", MiLB.com, October 7, 2020. 
- Brian McKenna: "Frank Shellenback", in Jacob Pomrenke, ed.: Scandal on the South Side: The 1919 Chicago White Sox, SABR, Phoenix, AZ, 2015, pp. 201-207. ISBN 978-1-933599-95-3