Like werewolves, worgen look like a cross between a human and a wolf. And, like werewolves, anyone bitten by them will inherit the curse, provided they survive. With sharp fangs, rending claws and animalistic speed, they kill anyone they see as prey or invading on their territory.
However, the playable worgen are a different sort of creature. The Greymane Worgen are a group who have found a partial cure which allows them to retain their sanity and intelligence whenever they transform in their worgen forms.
Identifying worgen can be tricky, with the most common traits being a certain sort of swept back dark mane, somewhat bat-like ears, often prominent fangs, and a rather pronounced snout. However, these things can vary dramatically by the artist's style. worgen can come in a wide array of doglike colors and patterns. Many worgen do not have tails, as this is how they are depicted in the game, however, early concept art showed them as having tails, and many players prefer that concept and include it in their artwork. As such, the presence or lack of a tail is not a clear indicator of a worgen.