Ian Ainsworth Cook (born May 1, 1960) is an American psychiatrist. He is an associate professor of Psychiatry and Biobehavioral Sciences at the University of California, Los Angeles's David Geffen School of Medicine. He is also a research scientist at the UCLA Neuropsychiatric Institute and the Brain Research Institute at UCLA. He serves as director of the UCLA Depression Research Program and associate director of the UCLA Laboratory of Brain, Behavior, and Pharmacology. Cook holds the Joanne and George Miller & Family Chair in Depression Research.