Eleanor Beatrice Marcy "Beazy" Sweeney ((1914-08-11)August 11, 1914–(1989-07-17)July 17, 1989) was an American plant physiologist and a pioneering investigator into circadian rhythms.
She was Professor, Emerita at University of California, Santa Barbara.
Having started her career as a botanist, serendipity led her to dinoflagellate research.
She investigated circadian rhythms in photoluminescent dinoflagellates, and other single celled organisms.
Later in her career she served as a senior officer in many scientific organizations, including the American Association for the Advancement of Science and the American Institute of Biological Sciences.