John Gustav Thompson (June 22, 1877 – March 28, 1958) was a pitcher in Major League Baseball. He played for the Pittsburgh Pirates and St. Louis Cardinals.
After his professional baseball career ended, Thompson moved to Kalispell, Montana around 1909 with his wife who was from Kalispell and remained there until his death nearly 50 years later in 1958. He was called "the father of baseball in Kalispell". He ran a pool hall, cigar store and a sports bar.