We captured 3 male federally endangered Myotis grisescens (Gray Bat) in the Cosby Creek area of Great Smoky Mountains National Park (GRSM) in Cocke County, TN, during summer mist-netting surveys (15 and 22 July 2016). Although GRSM is known for its diversity of bat species (n = 11), these specimens represent the first Gray Bats, and twelfth bat species, captured within the GRSM boundary. The documentation of this species is important, as it is the third federally listed bat species (along with Myotis sodalis [Indiana Bat] and Myotis septentrionalis [Northern Long-eared Bat]) known to occur within GRSM. We recommend further research be conducted on Gray Bats in GRSM to understand the species' habitat use and potential implications for park management.