Ryk Neethling (born 17 November 1977) is a South African swimmer. He won an Olympic gold medal in the 4×100 m freestyle relay at the 2004 Summer Olympics. He is the former joint owner of the 4×100 m freestyle relay world record and holds several South African records. He also is the first South African to compete four successive Olympic Games.
Neethling is also a trustee of the SEAL Open Water Swimming Development Trust whose other trustees include Ram Barkai, Theodore Yach, Andrew Chin and Annette Cowley. The trust obtains funds from the Youth Day Swim, part of the Freedom Swim Series.