Werewolves are humans that can transform into wolves. Some mythologies hold that werewolves transform involuntarily at the full moon; however, numerous werewolves in Vamp! have shifted their forms at will and not necessarily during the full moon.
Werewolves can partially or fully transform -- a good visual cue for when werewolves are prepared to transform into wolves is when their eyes become inhuman. They have superhuman senses of smell and hearing, and abnormal strength and speed compared to normal wolves. Their claws are noticeably strong as well (often compared to metals like iron and steel).
Certain werewolves (such as Watson) may have cravings for raw meat.
According to Vamp! IV, werewolves generally remain in human form, and most of them have human records.
The werewolves at Waldstein Castle are apparently impressively strong for werewolves. They (along with other supernatural beings such as witches and skeletons) serve the castle as familiars and bodyguards. Several of the werewolves have dyed their hair red and blue. Including the castle's personnel, there is a large werewolf population on the island of Growerth.
Some werewolves also serve the Clans as their subjugated servants alongside other species. A particular line of werewolves -- the Silver Wolves -- serve the Shreemeice Clan.