Marsh Hall, historically known as the Othniel C. Marsh House, is a historic house on Prospect Hill in New Haven, Connecticut. The property, which includes the house and a 6.8 acres (2.8 ha) grounds now known as Marsh Botanical Garden, was declared a National Historic Landmark in 1965. It was built in 1878 as the home of Othniel Marsh (1831–99), a leading 19th-century paleontologist, who occupied it until his death. The house is now owned by Yale University, and the building is occupied by the Yale School of the Environment.

Othniel Charles Marsh was an American professor of Paleontology in Yale College and President of the National Academy of Sciences. He was one of the preeminent scientists in the field of paleontology. Among his legacies are the discovery or description of dozens of new species and theories on the origins of birds.