The Werewolf Genocide was a campaign launched by the vampires to eradicate the werewolves. This campaign originated from the fact that a werewolf's bite is fatal to vampires. Very few werewolves escaped from this purge and the remaining ones formed packs to survive such as the pack formed by Jules, Brady and Mason Lockwood. The genocide happened a long time before modern times and the werewolves that survived were so few that even a majority of vampires believed them to be a mere legend.
- A Werewolf Genocide occurred in The Twilight Saga as well. The werewolves, known as the Children of the Moon, were also driven to near-extinction by vampires who saw them as a threat.
- Vanessa Monroe mentions that the werewolves are almost extinct, according to the legends in Bad Moon Rising. Katherine Pierce confirms her words when she has a conversation with Stefan in Memory Lane.
- Despite the fact that werewolves are supposedly almost extinct, they seem to have grown in numbers over the centuries. This is proved by the fact that Klaus has created multiple hybrids and given that the werewolf gene can lay dormant for generations. It's impossible to say for certain if they are as endangered as the show states.