James A. Estes (born 1945) is an American ecologist and Distinguished Professor at University of California, Santa Cruz (UCSC), known for his studies of sea otters and kelp forest ecology. Born in Sacramento, California, he graduated from the University of Minnesota in 1967, earned a Masters in Biology from Washington State University in 1969, and a Ph.D. in biology and statistics from the University of Arizona in 1974. He worked for the U.S. Fish and Wildlife Service and the U.S. Geological Survey from 1974 to 2007 before joining the UCSC faculty. He co-edited the books The Community Ecology of Sea Otters (1988), Whales, Whaling, and Ocean Ecosystems (2007), and Trophic Cascades: Predators, Prey, and the Changing Dynamics of Nature (2010), and is the author of Serendipity: An Ecologist's Quest to Understand Nature (2016). He was elected to the National Academy of Sciences in 2014.