|Actually a Moonrat but I like the picture|
Rather uninspiring isn't it. The Rat is found as an adversary in virtually every 1st level dungeon at least once. All in all they are rather boring. But that is why I like them. They are a work-horse of a monster for low levels. You can throw them into any type of adventure from a city adventure to a dungeon crawl and they make complete sense for being there all without needing to provide a reason. If skeletons (another favorite low level monster) are in a dungeon you need to explain what raised them as undead and why they are still there. If you use kobolds in the sewer of a city you need to explain how they have lived there so long undetected. Not so with the Rat.