Variola virus is a highly contagious virus from the family Poxviridae. The disease it causes is called smallpox, which was declared eradicated by the World Health Organization in 1980. Synonyms for this virus include the smallpox virus, variola, and the variola major virus. This virus is unique among the viral diseases due to its high mortality rate, with approximately 30% of infected persons dying from it. Its impact throughout human history has been devastating and telling of its potency. Although eradicated from the natural world, some fear that the virus could re-emerge through bioterrorism or other man-made means. Variola virus is a reminder of how important vaccination campaigns, monitoring and rapid response to epidemics, and global health efforts are.