Arthur W. Galston (April 21, 1920 – June 15, 2008) was an American plant physiologist and bioethicist. As a plant biologist, Galston studied plant hormones and the effects of light on plant development, particularly phototropism. He identified riboflavin and other flavins as the photoreceptors for phototropism, the bending of plants toward light, challenging the prevailing view that carotenoids were responsible.