Mary Kok (born in 1940 in Hilversum) is a former Dutch swimmer. Between 1954 and 1957 she set nine (mostly short course) world records in various freestyle, butterfly and medley events, six of them within one year (1955). She could not compete in the 1956 Summer Olympics due to the boycott of those games by the Netherlands. She was also not selected for the 1958 European Championships and switched to marathon swimming, becoming the first Dutch woman to cross the English Channel in 1960.