Orison S. Marden (October 20, 1911 – August 25, 1975) was an American lawyer and legal educator. He was born in New York State and graduated from Harvard Law School. Marden specialized in contract law, authoring the influential textbook 'Principles of Contract Law.' He taught at Columbia Law School and served on the American Law Institute. His work emphasized balancing contractual freedom with fairness, shaping mid-20th-century U.S. contract law. He also contributed to the Uniform Commercial Code. Marden's legacy endures in legal education and practice.