Werewolves and Hybrids
The werewolf curse is activated when a person with the werewolf gene kills someone whether on purpose or accident. Werewolves turn every full moon, and their bite is also fatal to vampires. Wolfsbane is lethal to werewolves.
Once Klaus became a hybrid, he found a way to make more hybrids. Once turned into a hybrid they have all the same strengths and weaknesses as Klaus, but they are also sired to Klaus, since Klaus's blood is the thing that turns werewolves into hybrids, they feel a sense of loyalty to him.
Tyler Lockwood
Tyler started out as just a wolf, he didn't even know that he had this gene until his dad passed away and his uncle came into town and Tyler got suspicious and started asking questions. Tyler is a main character and eventually becomes a hybrid because Klaus ends up turning him when trying to figure out how to turn wolfs into hybrids. He ends up resenting Klaus due to the sire bond but Tyler found out how to break the sire bond and was eventually free of Klaus. The only other wolfs besides Tyler is Haley and all the different wolf packs.
Haley Marshall
Haley is not a main character in vampire diaries, but she is in a couple of episodes. She is however one of the main characters on the originals. Haley starts out as a wolf, but she later gets pregnant with Klaus's child, and she dies during labor but due to the vampire blood in her system from her baby she becomes the first unsired hybrid.
