Sjaak Köhler
Jakob Frederik "Sjaak" Köhler (2 October 1902 – 19 June 1970) was a Dutch water polo player and swimmer. He finished in seventh and fifth place with the Dutch water polo team at the 1924 and 1928 Olympics; at both Games he played three matches and scored four and two goals, respectively. In 1924 he also competed in two freestyle swimming events (400 m and 4×200 m relay), but failed to reach the finals. His cousin Koos played water polo alongside Sjaak at the 1928 Olympics.