John Peet Conger (born September 26, 1994) is an American competition swimmer who specializes in butterfly and freestyle events. He is an Olympic gold medalist in the 4 × 200 m freestyle relay from the 2016 Summer Olympics in Rio de Janeiro and the current American record-holder in the 200-yard butterfly with a time of 1:37.35.

John Conger was born on September 26, 1994. Conger grew up in Rockville, Maryland where he swam for the Rockville-Montgomery Swim Club under head coach Sue Chen. In his later years, Conger attended and swam for Our Lady of Good-Counsel High School in the D.C. area. In his senior season at the 2013 Metro Championships, Conger broke the National High School Record in the 500-yard freestyle by three seconds, going 4:13.87. The former record of 4:16.39 held by Jeff Kostoff was the oldest High School Record in the books, set back in 1983. Conger is also the current National Independent High School Record Holder in the 100-yard freestyle with a time of 42.81.

At the 2012 U.S. Open Swimming Championships in Indianapolis, Conger took silver in the 200-meter backstroke with a time of 1:58.14. At the 2012 United States Olympic Trials, Conger missed the U.S. Team by finishing 8th in the 100-meter backstroke and 5th in the 200-meter backstroke with times of 54.63 and 1:58.97, respectively. At the 2012 Junior Pan Pacific Swimming Championships, Conger broke the national age-group (NAG) record for the 17–18 age group in the 100-meter backstroke with a winning time of 54.07. He also took home two more golds in the 200-meter backstroke (1:57.20), 50-meter freestyle (22.69), and one bronze in the 100-meter freestyle (49.84).

At the 2013 Summer Universiade in Kazan, Conger, competing as an incoming freshman, won gold in the 200-meter backstroke with a time of 1:55.47, and bronze as a member of the U.S. team in the 4x100-meter medley relay. Conger also competed in the 100-meter butterfly and finished 6th in the final.

Conger accepted an athletic scholarship to attend the University of Texas at Austin, where he swam for Hall of Fame Coaches Eddie Reese and Kris Kubik's Texas Longhorns men's swimming and diving team. On February 25, 2015, Conger broke the American and US Open record in the 200-yard butterfly with a time of 1:39.31 during a time trial at the 2015 Big 12 Championships.

At the 2015 NCAA Championships, Conger won the silver in the 100 (44.55) and 200 yard butterfly (1:39.74) behind teammate Joseph Schooling. He finished 7th in the 100 yard backstroke, with a time of 45.76. Conger helped the Texas Longhorns in the 400 yard medley relay (swimming the freestyle leg and recording an anchor time of 40.96), the 800 yard freestyle relay on Day 2, and the 400 yard freestyle relay (42.17 as the 2nd leg) on Day 3.

At the 2015 U.S Nationals in San Antonio, Conger competed in the 100 and 200 meter butterfly, the 200 m backstroke, the 100 m freestyle, and the 200 meter freestyle (only in the prelims). Conger finished second to Michael Phelps in both the 100 m and 200 m butterfly, recording times of 51.33 and 1:54.54 respectively. He narrowly missed his personal best in the 100 m freestyle, going 49.05 to miss it by .03. He finished second to Caeleb Dressel in that race. Conger qualified first after prelims in the 200 m freestyle, but withdrew to focus on the 200 butterfly. In the 200 m backstroke, Conger finished in 4th place with a time of 1:58.84.

Conger represented the United States in the 2016 Olympics in Rio, having qualified in the U.S. Olympic Trials winning bronze in the 200 meter freestyle. At the Olympics, Conger swam in the heats of the 4 × 200 meter freestyle relay and secured qualification for the final with a fast last 50 meter split of 26.83. Although Conger posted the fastest split time of the American team in the heats, he was left off the team that swam the final. The team went on to win the final, also earning Conger a gold medal.