Werewolf

The Sims
In The Sims Makin' Magic, there are two appearances of werewolves. They are accessible through the spell "Beauty or Beast". You can choose a werewolf look for both genders, and will change the Sim's looks to a werewolf. Becoming a werewolf is simply cosmetic, and lycanthropic Sims will interact normally with other Sims and they have no other noticible differences from normal Sims.

The Sims 2
Werewolves are Sims which have been imbued with Lycanthropy, a life state introduced in Pets. Sims can become Werewolves when bitten by the leader of the pack, a large wolf distinguishable by its dark coat, heavy build, and characteristic glowing yellow eyes. The leader only appears at night, and, as with all wolves, will be more likely to visit a Sim's lot if there are many trees and weed patches. A Sim must build a high relationship with the leader before he or she can be bitten. It is also rumoured that once FreeTime is installed that watching the scary movie "Werewolf" increases the chance of a wolf showing up on your lot. Without Free Time, you can increase the chance by adding many trees (not Seasons trees, just regular ones) to your lot. Lycanthropy can also be transferred using the Savage interaction.

Once a Sim has become a Werewolf, they will transform every night at 8:00 o'clock. Their Energy shoots up and their Hunger need plummets, sometimes making it a good idea to prepare a meal in advance; but this Hunger drop will never immediately kill the Sim. A Werewolf Sim can howl when selected, an action which lowers the Bladder need of all non-Werewolf Sims in the room by half. When outside, a Werewolf can also howl to summon wolves to the lot. Sims gain the Irritate > Grr! interaction which can be used against another Sim regardless of relationship and will lower his or her Bladder need. Werewolf Sims can even turn other Sims into Werewolves with the Savage interaction. Werewolves will transform back every morning at 6:00, disabling all Werewolf-specific interactions until nightfall.

The personality of Werewolf Sims will slowly shift over the course of a few days, eventually reaching 0 Neatness, 10 Outgoing, 10 Activeness, 10 Playfulness, and 0 Niceness; the Body skill will also increase. As such, Werewolves will tend to eat more quickly than other Sims and can even lick their plates clean when finished, but will rarely clean up after themselves, are notoriously messy in the shower, and cheat without instruction while playing chess.

Knowledge Sims naturally aspire to Werewolf-related wants, such as Sim howls, Become a Werewolf, and Turn Sim into Werewolf, while they fear being cured of Lycanthropy. A Sim with any other aspiration are exactly the opposite, fearing becoming a werewolf and wanting to be cured if turned. Interestingly, even if a Sim wants to become a werewolf, once they do, it will always appear as a bad memory.

Lycanthropy can be cured by purchasing the Lycanthropic-B potion from the obedience trainer, or from the gypsy if Nightlife or Apartment Life is installed. Unlike with the Vamprocillin-D potion, visiting Werewolf Sims cannot be influenced to drink Lycanthropic-B and must either be directed to do so on their home lot or taken control of via a game hack.

Werewolves may be better at training dogs or pets in general. This is still unconfirmed.

Biology
While there has not been much data on werewolf physiology released in The Sims 2, many things have been left to the players to find out.

During the day, werewolves appear as normal Humans, albeit with very canine-like personalities. This change in personality may be attributed to a change in brain chemistry, and/or an overbalance of certain hormones.

During the night, the Sim in question becomes, in essence, an anthromorphized wolf. Their howl ability causes a drop in the bladder need of non-werewolves, most likely an instinctual fear/defense mechanism. The transformation takes up a large amount of energy, reflected in the sudden drop in the hunger need of the Sim in question.