Donald James Baker (born March 23, 1937) is an American scientist who was trained as a physicist, practiced as an oceanographer, and has held science and management positions in academia, non-profit institutions, and government agencies.

He was a post-doctoral fellow in oceanography at the University of Rhode Island under John Knauss, who later preceded Baker as Under Secretary of Commerce and administrator of NOAA.

He was awarded a post-doctoral fellowship to work with Nobel Laureate Melvin Calvin at the Lawrence Berkeley Laboratory of the University of California on photosynthesis.

From Harvard, he joined the University of Washington in 1973, where he held a faculty position and co-founded and served as the first dean of the College of Ocean and Fishery Sciences.

He lectures regularly on the subjects of sustainability, climate change, and oceanography, has chaired numerous national and international advisory committees, and has testified frequently to the U.S. Congress.