Johannes "Jan" Marinus Plantaz (3 December 1930 – 10 February 1974) was a road and track cyclist from the Netherlands. He competed at the 1952 Summer Olympics in the road race (individual and team events) and 4 km team pursuit and finished in 22nd, 5th and 8th place, respectively. He won a bronze medal in the road race at the 1951 UCI Road World Championships.He died from a heart attack during training.