|By risk of extinction|
Extinct in the Wild (List)
|Critically Endangered (List)
|At lower risk|
|Conservation Dependent (List)
Near Threatened (List)
IUCN Red List
International Union for Conservation of Nature
Lists of organisms by population
Critically Endangered is the highest risk category assigned by the IUCN Red List for wild species. Critically Endangered species are those that are facing a very high risk of extinction in the wild. There are currently 2129 animals and 1821 plants with this assessment, compared with 1998 levels of 854 and 909, respectively.
As the Red List does not consider a species extinct until extensive, targeted surveys have been conducted, species which are possibly extinct are still listed as 'Critically Endangered'. A new ideal category for 'Possibly Extinct' has been suggested by BirdLife International to categorize these taxa.
IUCN definition 
To be defined as critically endangered in the Red List, a species must meet ANY of the following criteria (A–E) ("3G/10Y" signifies three generations or ten years—whichever is longer—over a maximum of 100 years; "MI" signifies Mature Individuals):
- A: Occurring over less than 100 km² and two of:
- 1. Severe habitat fragmentation or existing at just one location
- 2. Decline in extent of occurrence, area of occupancy, area/extent/quality of habitat, number of locations/subpopulations, or amount of MI.
- 3. Extreme fluctuations in extent of occurrence, area of occupancy, number of locations/subpopulations, or amount of MI.
- B: As above, but less than 10 km² (used to show differing levels of severity).
- C: Declining population of less than 250 MI and either:
- 1. A decline of 25% over 1G/3Y;
- 2. Extreme fluctuations, or over 90% of MI in a single subpopulation, or no more than 50 MI in any one subpopulation.
- D: Numbers less than 50 MI.
- E: At least 50% chance of going Extinct in the Wild over 3G/10Y.
See also 
- Lists of IUCN Red List Critically Endangered species for lists ordered by taxonomic rank
- Category:IUCN Red List critically endangered species for an alphabetical list
- The World's 25 Most Endangered Primates
- The world's 100 most threatened species
- IUCN for additional information on the IUCN
- "Apes extinct in a generation". BBC. 2005-09-01. Retrieved 2005-09-01.
- IUCN (2012). "IUCN Red List version 2012.2: Table 2: Changes in numbers of species in the threatened categories (CR, EN, VU) from 1996 to 2012 (IUCN Red List version 2012.2) for the major taxonomic groups on the Red List" (PDF). Retrieved 2012-12-31.
- IUCN (9 Feb 2000). "IUCN Red List Categories and Criteria, Version 3.1" (PDF). Retrieved 2012-12-31.