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- Wayne Chatfield-Taylor, president of the Export-Import Bank, undersecretary of commerce
- Blair Clark, journalist, former general manager, CBS News
- Ernest Amory Codman pioneering surgeon who made contributions to a variety of specialties and the study of medical outcomes
- Nick Clements, American theoretical linguist specializing in phonology, notably with CNRS in Paris
- William G. Congdon, representationalist painter who used Abstract Expressionism techniques
- Harry Crosby, poet and founder of the Black Sun Press
Read more about this topic: List Of St. Mark's School (Massachusetts) Alumni