John Martin (February 27, 1935 – June 18, 1993), was an oceanographer.
Born in Old Lyme, Connecticut, he is best known for his research on the role of iron as a phytoplankton micronutrient, and its significance for so-called "High-Nutrient, Low Chlorophyll" regions of the oceans.
He is also known for advocating the use of iron fertilization to enhance oceanic primary production to act as a sink for fossil fuel carbon dioxide.
John Martin died from prostate cancer at the age of 58.