Markus Thormeyer (born August 25, 1997) is a Canadian competitive swimmer who specializes in freestyle and backstroke.

At 15 he competed at the 2013 Canada Summer Games for Team British Columbia, where he earned a bronze in the men's 100m backstroke.

[4][5] It was not until 2015 when Thormeyer made his first senior international appearance at the 2015 Pan American Games where he won a silver as a part of the 4x100 m freestyle relay.

Later that year in December, Thormeyer won a bronze medal as part of Canada's 4x50m mixed freestyle event alongside Sandrine Mainville, Michelle Toro, and Yuri Kisil at the World Short Course Championships in Windsor, Ontario.

[15] The onset of the COVID-19 pandemic resulted in the 2020 Summer Olympics being delayed by a year, as well as causing significant disruptions in Thormeyer's training.

[20] Notably, Thormeyer was part of Canada's team in the 4 × 100 m freestyle relay, who unexpectedly finished in fourth place despite not having been favoured to make the event final.