1. International Union for Conservation of Nature (IUCN): The IUCN is a global authority on the status of the natural world and the measures needed to safeguard it. It is the world's largest and oldest environmental organisation, with over 1,300 government and NGO members. The IUCN Red List is the world's most comprehensive information source on the global extinction risk status of animal, plant and fungus species.
2. World Wildlife Fund (WWF): WWF is one of the world's largest and most respected conservation organisations, with over 5 million supporters and a global network active in over 100 countries. WWF's mission is to conserve nature, wildlife, and habitats, and to build a future where humans live in harmony with nature.
3. The Nature Conservancy: The Nature Conservancy is a leading conservation organisation that works to protect ecologically important lands, waters and wildlife. It is the largest environmental non-profit in the United States and has more than 1 million members. The Nature Conservancy has protected more than 125 million acres of land in the United States, Latin America, Asia-Pacific, Africa, and the Caribbean.
4. Conservation International (CI): CI is a non-profit organisation dedicated to protecting nature, focusing on biodiversity hotspots around the world. It works with local communities, governments, and businesses to develop sustainable solutions to environmental challenges.
5. Zoological Society of London (ZSL): ZSL is an international scientific, conservation and educational charity committed to the worldwide conservation of animals and their habitats. It operates two conservation parks in London and runs field projects in over 50 countries around the world.
These are just a few examples of organisations working to protect endangered species. There are many other smaller and local organisations also contributing to conservation efforts around the world.