​Nature's Greatest Defender is a 2009 documentary that chronicles the life and work of renowned American zoologist and wildlife biologist George Schaller. Over a career spanning more than five decades, Schaller has been instrumental in the conservation of some of the world's most endangered species, including mountain gorillas, lions, and pandas. The film follows Schaller as he revisits the sites of his groundbreaking studies, reflecting on the current state of these species and their habitats. Narrated by Glenn Close, the documentary offers an intimate look into Schaller's unwavering dedication to wildlife conservation.