Once nothing but roadkill in the school trash bin, this flat-as-a-pancake rat gets a second chance at life when Edgar brings him back from the dead. No longer an ordinary pest, the dumpster menace has been transformed into a muscular Were-rat that walks on his hind legs and displays long, sharp fangs. Like a real rat, Were-Rat has no loyalty to his creator. The Were-Rat is a minor antagonist of the movie.
- Since the other monsters are meant to bare a resemblence to the original Universal Movie monsters, the Were-Rat is meant to resemble the Wolf-Man from The Wolf Man . Ironically, Bela Lugosi, the man who played Ygor from Son of Frankenstein, also plays a part in The Wolf Man.
- In this movie, he is voiced by Dee Bradley Baker.
- The Were-Rat resembles the werewolf from The Nightmare Before Christmas.