Chase Tyler Kalisz (/ˈkeɪlɪʃ/ KAY-lish; born March 7, 1994) is an American swimmer who specializes in individual medley events. He is an Olympic gold medalist in the 400-meter individual medley at the 2020 Summer Olympics in Tokyo, an Olympic silver medalist at the 2016 Summer Olympics in Rio de Janeiro and a two-time World Aquatics Championships gold medalist.

Kalisz attended the University of Georgia from 2012 to 2017 and competed for the Georgia Bulldogs swimming and diving team where he was a three-time NCAA Champion and the current American record-holder in the 400-yard individual medley.

Kalisz graduated from Fallston High School in Fallston, Maryland.

In August, at the 2012 Junior Pan Pacific Swimming Championships conducted at the Veterans Memorial Aquatic Center in Honolulu, Hawaii, Kalisz was the Junior Pan Pacific champion in both the 200 meter individual medley, where he won the gold medal with a Championships record of 1:59.51, and the 400 meter individual medley, where he won the gold medal in a Championships record time of 4:12.59, as well as a silver medalist in the 4×200 meter freestyle relay with a final relay time of 7:19.89. Additionally, he placed second in the B-final of the 200 meter freestyle with a 1:51.93 after swimming a 1:50.14 in the preliminaries. He served as a captain for Team USA at the Championships.

During his first season of collegiate swimming for the Georgia Bulldogs, Kalisz won his first NCAA title in the 400 yard individual medley with a time of 3:38.05 at the 2013 NCAA Division I Men's Swimming and Diving Championships. His swim made him the sixth fastest swimmer in the race in history and the fastest at his age. Kalisz also set a new school record in the event for the University of Georgia, lowering his former school record by over 1.7 seconds.

Kalisz's qualification for the 2013 World Championships team at the 2013 US National Championships made him the fifth Georgia Bulldog in history to reach that stage of international swimming competition. He qualified to compete in one event, the 400 meter individual medley, when he won the national title in the event at the year's national championships with a personal best time of 4:11.83. At the 2013 World Aquatics Championships in Barcelona, Spain, Kalisz won the silver medal in the 400 meter individual medley, finishing with a time of 4:09.22, dropping over two full seconds off his previous best time, and touching the wall less than six tenths of a second behind the gold medal winner, Daiya Seto of Japan. Kalisz's swims at the US National Championships and World Championships were fast enough for him to make the 2013—2014 national team in both the 200 meter individual medley and the 400 meter individual medley. In November, Kalisz won USA Swimming's Golden Goggle Award for "Breakout Performer of the Year" for his accomplishments at the international and national levels in 2013.

At the 2014 NCAA Championships in Austin, Texas in March, Kalisz successfully defended his title and broke the American record in the 400 yard individual medley, also called the 400 yard IM, previously set in 2009 by Tyler Clary, with a time of 3:34.50. In addition to setting a new American record, his time also set new US Open, NCAA, school, and pool records. The pool record he set for the Lee and Joe Jamail Texas Swimming Center stood through the duration of the 2019 NCAA Championships where the fastest swimmer was almost two full seconds off Kalisz's mark.

In his junior year of collegiate swimming for the Georgia Bulldogs, Kalisz placed second in the 400-yard individual medley, behind Texas Longhorns' Will Licon, finishing well off his best time in 3:39.51. Kalisz's coach at the time, Bob Bowman, dubbed Kalisz's third swimming season in college, the 2014–2015 school year, a "pretty terrible third year".