Johannes ("Han") Nicolaas Maria Kulker (born 15 August 1959 in Leidschendam, Zuid-Holland) is a former Dutch middle distance runner, who won a bronze medal at the 1986 European Championships in Athletics in Stuttgart over 1500 metres. The race was won by Steve Cram.Two years later, Kulker finished sixth in the 1500 m final of the 1988 Summer Olympics in Seoul, where Peter Rono won gold. In 1987 Kulker won the bronze medal at the World Indoor Championships in Athletics over 1500 metres.