Ryk Neethling (born November 17, 1977) is a South African swimmer and the winner of an Olympic gold medal.

Born in Bloemfontein, he attended the prestigious Grey College, where he excelled in swimming, earning a place in the South African swimming team for the 1996 Summer Olympics in Atlanta, where he came fifth in the 1500 m freestyle.

Immediately following the Games he was enrolled at The University of Arizona in the United States of America, where he further cemented his swimming reputation, earning a numerous awards and accolades, including being the 9 times NCAA National Champion, Arizona Athlete of the Year and PAC-10 Athlete of the Year for four consecutive years, 1999 NCAA Swimmer of the Year, and the University of Arizona Athlete of the Century award.

He continued his international career at the 1998 Commonwealth Games, winning the silver medal in the 1500 m freestyle, but only managing fifth at the 1998 Fina World Championships. In 1999 he had a much better Pan Pacific Championships winning silver in the 1500m freestyle, and bronze in the 400m and 200m free. After achieving a disappointing 5th in the 1500 m freestyle event and 8th in the 400 m freestyle at the 2000 Summer Olympics in Sydney he elected to discontinue competing in the 1500 m event, concentrating instead on the 50 m and 100 m freestyle events. At the 2002 Commonwealth Games he won a bronze medal in the 100 m freestyle and came 4th in the 50 m freestyle events. At the 2006 Commonwealth Games he won silver in the 100m freestyle and was part of the S.A gold medal winning 4x100m freestyle relay team.

He currently holds the South African record in the 200 m, 400 m, 800 m and 1500 m freestyle events, and is the joint holder of the 4x100 m freestyle relay world record.

The highlight of his career thus far has been winning a gold medal in the 4 x 100 m freestyle relay at the 2004 Summer Olympics. He also placed 4th in the individual 100m freestyle

Ryk dated American swimmer, and fellow Olympic gold medallist Amanda Beard for nearly six years, with the relationship ending in the Spring of 2005.

In November 2005, he announced that he had refused a multimillion dollar offer by Qatar's Olympic body to switch nationalities and swim for Qatar at the 2008 Beijing Olympics.

Now he is back to Tucson to prepare for the 2008 Beijing Olympic game.