Peter Vanderkaay (born February 12, 1984) is an American Freestyle swimmer, who won a gold medal at the 2004 Summer Olympics. Vanderkaay competed on the 4x200m freestyle relay team of Michael Phelps, Ryan Lochte, and Klete Keller, that upset the favored Australian team of Ian Thorpe, Grant Hackett, Michael Klim, and Nicholas Sprenger. The same American relay would go on to set an American Record in the same event at the FINA 2005 World Aquatics Championships in Montreal, Canada.

At the 2007 FINA World Championships in Melbourne, Vanderkaay again helped the relay of Lochte, Phelps, Keller and himself set a World Record in the 4x200m Freestyle Relay, beating the second place Australian team by over 10 seconds. This American relay is undefeated over this distance since the Athens Games.

While primarily a mid-distance to distance freestyle swimmer, Vanderkaay is capable of swimming well in every freestyle distance from the 50 to the mile, as well as the 400 I.M. (Individual Medley). Vanderkaay is the current Michigan High School State and NCAA Record holder in the 500-yard freestyle (set in 2002 and 2006 respectively).