Frederik Carlo Hviid Köhler (born 9 November 1974 in Las Palmas, Gran Canaria) is a former long-distance freestyle and medley swimmer from Spain who competed at two consecutive Summer Olympics for his native country, starting in 1996.

He won the gold medal both in the 400m IM long course at the 1999 European Aquatics Championships in Istanbul, Turkey and in the 1999 short course edition in Lisbon.

In February 2017 he was inducted into the Stafford H. "Pop" Cassell Hall of Fame Archived 17 March 2017 at the Wayback Machine.

He participated in the 2014 Masters World Championships in Montreal, Canada and won gold in both the 800m freestyle and the 200m backstroke.

Fred is currently an assistant swim coach for the Monocacy Aquatic Club (MAC) in Frederick, MD.