John Carl Thomson (born October 1, 1973) is an American former starting pitcher who last played for the Kansas City Royals of Major League Baseball.

He went undrafted out of high school and pitched for McNeese State University (Lake Charles, Louisiana) in 1992 and Blinn Junior College (Brenham, Texas) in 1993.

In addition to the Rockies, he has played for the New York Mets, Texas Rangers, Atlanta Braves and Kansas City Royals and also pitched in the Toronto Blue Jays organization from April through June 2007.

[2] In his major league debut May 11, 1997, Thomson gave up three runs (only one earned) on five hits in 72⁄3 innings with 7 strikeouts and 4 walks in a 3–1 loss to the Philadelphia Phillies.

With the Rockies unlikely to compete for a National League playoff spot and Thomson a free agent at the end of the season, he became a target of trade talks as the July 31 non-waiver deadline approached.

Thomson was again granted free agency in October 2003 and signed a two-year contract (including a club option for a third year) with the Atlanta Braves December 9.

[10] An MRI eventually revealed some fraying of his labrum[11] and he made only one more appearance for the Braves, pitching an inning of relief September 27.

[12] The team placed him on the disabled list at the end of spring training with a recurrence of his shoulder injury[13] and released him June 20 before he ever made an appearance with the major league club.

[14] Thomson was signed by Kansas City on June 22, 2007, and replaced the injured Scott Elarton in the Royals' starting rotation.