Jacobus Hermanus Hendrik Jan "Koos" de Jong (7 April 1912 – 20 August 1993) was a sailor from the Netherlands.

He competed in the Firefly event at the 1948 Olympics and in the Finn event at the 1952 Games and won a bronze medal in 1948, placing fourth in 1952.

[1] De Jong won several medals at European championships, including the gold in 1959.

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