Karissa Schweizer (/ˈʃwaɪtsər/ SHWYTE-sər; born May 4, 1996)[1] is an American middle- and long-distance runner, Olympian and World Record holder in the women's 4x1500 meters relay.

She is the daughter of Mike and Kathy (Petricka) Schweizer, both of whom had successful collegiate track careers at Mankato State, with her father earning All-American honors.

[10] Despite this, Schweizer defeated favorites Erin Finn and Anna Rohrer to win the 6 kilometer race in 19:41.6, becoming the first female national champion in any sport in Missouri Tigers history.

[3][17] In the 2018 NCAA Division I Outdoor Track and Field Championships, Schweizer ran 32:14.94 in the 10,000m to finish third, twelve seconds under the existing meet record, set by Sylvia Mosqueda thirty years earlier.

[20] Schweizer, running the fastest time 5K in the U.S. during the summer season, recorded a personal best 15:01.63 during a win at the Sunset Tour on July 10, 2019, in Azusa, California.

[22] On July 10, 2020, Schweizer finished second to Shelby Houlihan in a 5000 m race conducted by the Bowerman Track Club with a new personal best of 14:26.34.

On July 23, 2020, Schweizer set a new world leading time in addition to a new personal best in the 1500m, at 4:00.02, which made her the 8th fastest American to ever run the event, finishing in front of Colleen Quigley and Courtney Frerichs in 4:03.98 and 4:07.39, respectively.

The record was ratified in December 2020,[23][24] On June 21, 2021, in 94-degree heat in Eugene, Oregon, Schweitzer finished 0.3 seconds behind Bowerman Track Club teammate Elise Cranny in the 5000m, qualifying for the U.S. Olympic team with a 15:28.11.

[26] On May 27, 2022, at the Prefontaine Classic in Eugene, competing in the 10,000m event, Schweitzer and Alicia Monson ran together for the last 5,000 meters, which they covered in under 15 minutes.