[File:Whale shark Georgia aquarium.jpg|thumb|360px|right|alt=Photo of shark in profile surrounded by other, much smaller fish |The whale shark, the world's largest fish, is classified as Vulnerable.

]]  Threatened sharks are those vulnerable to endangerment (extinction) in the near future. The International Union for Conservation of Nature (IU) is the world’s oldest global environmental organization. It evaluates threatened species, and treats threatened species not as a single category, but as a group of three categories, depending on the degree to which they are threatened: