Karl Johan Erik "John" Jansson (18 July 1892 – 10 October 1943) was a Swedish diver, who competed at the 1912, 1920 and 1924 Summer Olympics.In 1912 Olympics he won a bronze medal in the plain high diving event, was seventh in the 3 metre springboard, and was eliminated in the heats of 10 metre platform event. Eight years later he won a bronze medal in the plain high diving event and was sixth in the 3 metre springboard. In 1924 he won a silver medal in the plain high diving event.