Zdeněk Koubek (born Zdena "Zdeňka" Koubková, 8 December 1913 – 12 June 1986) was a track athlete from Czechoslovakia.

In 1935, Koubek retired from competition, announcing his intention to live as a man,[3] and underwent a series of medical examinations.

[1][4] He abandoned athletics and a potential coaching career, and only after World War II did he join the team of his brother Jaroslav to play rugby for a local club.

A 1935 novel Zdenin světový rekord (Zdena's world record) by Lída Merlínová is based on his early life and career.

[1][5] The book The Other Olympians: Fascism, Queerness, and the Making of Modern Sports (2024), published by Macmillan and written by journalist Michael Waters, delves into the story of Koubek and other early Olympic trans, intersex and gender-diverse athletes, placing them in relation to the 1936 Summer Olympics and the bureaucratization and catalogation of gender in sports.