Lycanthropes or Werebeasts are villains who change, temporary or permanently, into werebeasts, such as werewolves, werecats, werehyenas, wererabbits, werebears, etc. They are well-known choices for villains, with the classic Werewolf being the most popular and common variant by far.

In some cases, werebeasts are not necessarily evil, as some characters after a transformation might have complete control over themselves, or at the very least, their morality. Although in most cases, werebeasts are more commonly implemented as villains, due to their berserk, chaotic and murderous nature, with their original selves completely taken over. Werebeasts who transform back into their normal form often have no memory of their time as a werebeast.

One of the most well-known causes for characters becoming werecreatures in media are curses placed upon them. Ingesting certain chemicals and experimental mishaps are also popular causes. Characters are who were not necessarily villainous to begin with may have the ability to transform into a lycanthropic creature; acting as their destructive and even murderous alter-ego.

The trigger of an already-cursed individual becoming a werewolf can also greatly differ in media, with the most famous being the witnessing of a full moon. Some individuals can transform into a werecreature and revert at will, even maintaining their original personality and intelligence when fully transformed. This can be seen in many video games, with one example being the Dragonborn in The Elder Scrolls: Skyrim.

Much like the origin and mechanics of becoming a lycanthrope, these creatures can have various weaknesses. The one most common weakness in folklore are weapons made of silver.