Guy Marcos Barnea (Hebrew: גיא ברנע; born 9 September 1987) is an Israeli swimmer who represented Israel at the 2008 Summer Olympics, and has won three medals at the European Championships.

[2] Barnea trained at The Race Club, a swim camp in Florida founded by Olympic swimmers Gary Hall, Jr. and his father, Gary Hall, Sr. train elite swimmers across the world in preparation for the 2000 Sydney Olympic Games.

[8][14] In August 2014 at the Israeli national swimming championships Barnea won a gold medal in the 50m backstroke with a time of 25.12.

[8] In August 2016 he won the gold medal at the Eindhoven Swim Cup (Dutch Championships) in the 100m backstroke, with a time of 55.19.

[17] At the 2017 Scottish National Championships, Barnea won the men’s 100m backstroke in a time of 54.49, close to his lifetime personal best of 54.29.