100 of the World's Worst Invasive Alien Species is a list of invasive species compiled in 2000 from the Global Invasive Species Database, a database of invasive species around the world.[1][2] The database is run by the Invasive Species Specialist Group (ISSG) of the International Union for Conservation of Nature (IUCN). The ISSG acknowledges that it is "very difficult to identify 100 invasive species from around the world that really are 'worse' than any others. ... Absence from the list does not imply that a species poses a lesser threat."[1] In 2013, the ISSG updated their list to supersede the recently eradicated † rinderpest virus, and a few genus and species names were altered.