| Birth Date: | 10 December 1914 |
| Birth Place: | Kansas City, Missouri, United States |
| Death Place: | Oklahoma, United States |
| Club: | University of Iowa |
Jack George Sieg (December 10, 1914 – December 21, 1968) was an American swimmer who used the butterfly stroke in 1935,[1] developed by his coach Dave Armbruster.[2] He competed for the University of Iowa[3] and first used the stroke in a breaststroke leg of a medley relay February 25, 1935.[4]