Weston "Seth" Kelsey (born August 24, 1981 in Santa Monica, California) is an American épée fencer and three time Olympic fencer. He competed at the 2004, 2008 Summer Olympic Games and 2012 Summer Olympic Games. He finished 4th in the individual competition at the 2012 London Olympics.
He finished 17th in the individual competition at the 2008 Beijing Olympics. He has competed at the World Fencing Championships since 2003. His best results were seventh at the 2010 World Fencing Championships in Paris, France. He was a member of the American team that won the silver medal in team épée at the 2010 World Championships and a member of the American épée team that won the 2012 World Championships in Kiev, Ukraine. He competed in the 2012 Olympics at London, losing his semi-final 5 - 6 to eventual champion Ruben Limardo. He went on to compete against Korean épée fencer Jung Jin-Sun in the bronze medal match, losing 11 - 12 in the sudden death priority minute.