John Todd Zimmer (February 28, 1889 in Bridgeport, Ohio – January 6, 1957 in White Plains, New York) was a leading American ornithologist.A graduate of University of Nebraska-Lincoln, he took an early interest in both entomology and ornithology. From 1913 he worked as an agricultural adviser in the Philippines and later New Guinea, during which time he made important collections of bird specimens.