The 1288-km² Great Smoky Mountains National Park (the Park) is one of the largest protected temperate forest ecosystems east of the Rocky Mountains. Because of its global ecological importance, the Park was designated an International Biosphere Reserve in 1976 and a World Heritage Site in 1983. The Park's rich biodiversity is the result of a deeply dissected landscape ranging in elevation from 259 m (850 ft) to 2026 m (6643 ft), high primary productivity, and diverse plant communities. These conditions, and the occurrence of several species at or near their southern range limit, favor high mammal diversity in the Park. Herein, I present the first comprehensive update on the Park's mammals in over 20 years. Since that 1995 publication, several new species have been recorded, additional distribution and other ecological data collected, 3 reintroductions (2 successful, 1 unsuccessful) transpired, and numerous taxonomic revisions have occurred. To the extent that data is available, the distribution, food, reproduction, pelage, hibernation, predation, parasites, measurements, and location of specimens are given for all 68 mammals in the Park. Four additional mammal species are listed as “probable” based on their known distribution in regions surrounding the Park. The Literature Cited along with the additional listed references provided in Appendix 1 together comprise the most complete bibliography ever assembled relating to mammals found in the Park.