Koi Sie Yan

Koi Sie Yan (born 8 February 1999) is a Malaysian rhythmic gymnast.

Career
Koi first competed for Malaysia at an international rhythmic gymnastics championship in 2015 where she represented Malaysia at the 2015 World Rhythmic Gymnastics Championships. Koi also went onto compete at the 2015 Southeast Asian Games and claimed her maiden Southeast Asian Games medal after securing a gold medal in the women's individual all-around event. At the 2017 Southeast Asian Games which was held in her home nation at Kuala Lumpur, she achieved four gold medals and a silver medal in the rhythmic gymnastics events.

She represented Malaysia at the 2018 Commonwealth Games which was her maiden Commonwealth Games appearance and competed in the rhythmic gymnastics discipline. Koi claimed four medals at the 2018 Gold Coast Commonwealth Games including 3 silver medals in the Team, individual ball event and individual clubs event along with a bronze medal in the individual ribbon event.

She was again selected to represented Malaysia at the 2022 Commonwealth Games, ending in 4th in the team event and qualifying for the ribbon final with a score of 25.750.

In December 2023, the Malaysian Gymnastics Federation announced plans to engage Koi and Izzah Amzan as assistant coaches to the national team.