John David Gillanders (born May 18, 1939) is an American former competition swimmer, Olympic medalist, and former world record-holder. He represented the United States at the 1960 Summer Olympics in Rome, Italy, where he won a bronze medal in the men's 200-meter butterfly, finishing behind fellow American Mike Troy and Australian Neville Hayes.
He still continues to swim in Masters swimming competitions where has been in the top ten of his age group for most of the last 35 years. He set a world record in the short course 100-meter butterfly in 1986 for the 45-49 age group. Most recently he placed in the top ten of several events during the 2010 USMS Spring National Championships in May and in the Summer Championships in August.