Ksawery Masiuk

Ksawery Masiuk ( Polish: ; born 17 December 2004) is a Polish swimmer who specializes in the backstroke. He won bronze medals at the 2022 World Aquatics Championships and two silver and one bronze medals at the 2024 European Aquatics Championships.

Career
He started his professional career as a swimmer in 2012 in the UKS Start Wola Rzendzińska club trained by Henryk Iwaniec. In 2013, he began representing BOSiR Brzesko under coach Marcin Kacer. In 2017, he moved to Warsaw where he attended the Janusz Kusociński Sports High School No. 59 and entered the G-8 Bielany Warszawa club under his current coach Paweł Wołkow.

In 2021, he participated at the Polish Aquatics Championships in Lublin and won gold in the 50 m backstroke with the 25.14 seconds result setting a new national record for 17-year olds, which allowed him to qualify for the World Aquatics Championships in Budapest.

In the same year, he won gold medal at the European Junior Swimming Championships in Rome in the 100 meters backstroke by achieving 53.91 seconds. In the 50 meters event, he finished second with the 25.28 seconds result.

He won gold medals at the 2022 FINA World Junior Swimming Championships in Lima, Peru, in the 50 and 100 meter backstroke events. He also won gold medals in the 4x100 meters medley and 4x100 meters mixed medley alongside Karolina Piechowicz, Krzysztof Chmielewski and Paulina Cierpiałowska.

He won a bronze medal at the 19th FINA World Championships in Budapest in 2022, was briefly upgraded to silver after the disqualification of American swimmer Justin Ress and returned to bronze after Ress was reinstated.

In 2023, he came fourth in the 50 meters backstroke event at the World Aquatics Championships in Fukuoka, Japan, falling 0.07 seconds short of bronze medal.

In 2024, he won two silver and one bronze medals at the European Aquatics Championships in Belgrade in the 50 m backstroke, 4x100 m medley and 100 meters backstroke respectively.