Fenny Heemskerk (3 December 1919 in Amsterdam[1] – 8 June 2007 in Amersfoort) was a Dutch chess player.

She won the female Dutch Chess Championship ten times (1937, 1939, 1946, 1948, 1950, 1952, 1954, 1956, 1958 and 1961).

[5] She played in the 1st Women's Chess Olympiad at Emmen 1957 – but had to withdraw after only two days upon learning her father had died.

[6] In 1989, at the age of 70 she participated in the Moscow GMA qualifiers alongside strong male Grandmasters.

In January 1940 Heemskerk married FIDE Master Willem Koomen[8] and soon gave birth to a daughter.