100 of the World's Worst Invasive Alien Species

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. 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." In 2013, the ISSG updated their list to supersede the recently eradicated † rinderpest virus, and a few genus and species names were altered.

Criteria for inclusion
Two criteria were used in selecting items for the list:
 * An invasive species' "serious impact on biological diversity and/or human activities," and
 * That species' "illustration of important issues surrounding biological invasion".

According to the ISSG, "only one species from each genus was selected." However, the renaming of Clidemia hirta now implies two Miconia species in the list.

List of species
This list has been updated to reflect later changes in taxonomy, to ensure alphabetical order of genera, and to remove apparent errors. Common names may be ambiguous.