Wilhelmina "Willy" den Turk (3 April 1908[1] – 19 June 1937[2][3]) was a Dutch swimmer.

She won a gold medal in the 100 m backstroke and a silver in the 4×100 m freestyle relay at the 1927 European Aquatics Championships.

The same year she set a world record in the 100 m backstroke.

[4] Den Turk was selected for the 100 m backstroke and the 4×100 m medley relay at the 1928 Summer Olympics,[5] but had to withdraw due to a foot injury.

[2][6] She retired shortly thereafter, married Henri Emil Lagerman in 1930, and in 1933 gave birth to a son.