Bats have populated earth for approximately 52 million years, serving as natural reservoirs for a variety of viruses through the course of evolution. Transmission of highly pathogenic viruses from bats has been suspected and linked to a spectrum of emerging infectious diseases in humans and animals worldwide. Examples of such viruses include Marburg, Ebola, Nipah, Hendra, Influenza A, Dengue, Equine Encephalitis viruses, Lyssaviruses, Madariaga and Coronaviruses, involving the now pandemic Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Herein, we provide a comprehensive review on the diversity, reservoirs, and geographical distribution of the main bat viruses and their potential for cross-species transmission.