T. Colin Campbell is an American biochemist, born on March 14, 1934, who specializes in the effect of nutrition on long-term health. He is the Jacob Gould Schurman Professor Emeritus of Nutritional Biochemistry at Cornell University.

Campbell is renowned for his advocacy of a low-fat, whole foods, plant-based diet. He coined the term "Plant-based diet" in 1980 to present his research on diet at the National Institutes of Health. He has authored over 300 research papers and four influential books, including The China Study (2005), co-authored with his son Thomas M. Campbell II, Whole (2013), The Low-Carb Fraud (2014), and The Future of Nutrition (2020). Campbell was also featured in the 2011 documentary Forks Over Knives.

He was a lead scientist in the China–Cornell–Oxford Project, initiated in 1983, to explore the relationship between nutrition and chronic diseases like cancer, heart, and metabolic diseases. This study, conducted by Cornell University, the University of Oxford, and the Chinese Academy of Preventive Medicine, was described by The New York Times as "the Grand Prix of epidemiology".