Although humans are affected by an enormous range of microorganisms, almost all newly discovered emerging pathogens are viruses that are often zoonotic or vector-borne. These emerging viruses often have high baseline mutation rates, allowing them to adapt relatively easily to new hosts and enabling them to take advantage of new epidemiological opportunities provided by the changing environment. A range of apparently new human viral pathogens has been reported increasingly in international outbreak information over the last few years. How they will influence global public health remains to be seen. Emerging viruses that might be of particular global public health importance include, respiratory coronaviruses, Zika virus, and severe fever and thrombocytopenia syndrome virus. Other emerging viruses of importance include bocavirus, Bufavirus, PARV4, human parechovirus, Itaya, Heartland, and Bourbon virus. The human pathogenicity of other emerging viruses is less certain.