Melvin "Mel" Nash (born c. 1955) is a retired American swimmer who won a gold and a bronze medal at the world championships in 1973 and 1975. He also won the 100 m backstroke event at the 1971 Pan American Games. In 1972, he was chosen by the Swimming World Magazine as the national high school swimmer of the year.
Nash has a daughter Kathryn and son Mel II; both are competitive swimmers. Nash senior himself continued competing in the 1980s in the masters category. He lives in Jacksonville, Florida, where together with his wife runs the North Florida Swimming club.