Monster

The term monster is used by the Clan cats for cars, trucks, or other vehicles that Twolegs ride in. They believe they are living creatures which "swallow" the Twolegs and carry them across roads, which the Clans know as Thunderpaths. Monsters usually stick to the Thunderpaths, but have left it for certain memorable events such as the destruction of the forest in the New Prophecy Series. The warriors think that the headlights of vehicles are their eyes, and the Twolegs ride in their belly. When a car is parked, they are said to be sleeping. The Clans do make some distinctions between different types of monsters; they recognize the difference between normal monsters and the bulldozers used to tear up the forest (tree-eaters), and they occasionally refer to motor boats as water-monsters.

Fire and Ice

 * When Fireheart tells Cinderpaw not to go to the Thunderpath, she does anyway and gets hit by a monster. She is not killed, however her leg is severely injured and Yellowfang says that she will live, but she will be permanently handicapped and can never be a warrior. She feels that she is a burden to the clan, but eventually she becomes Yellowfang's apprentice as a medicine cat.

Rising Storm

 * A Twoleg monster hits Whitethroat on the Thunderpath when he is running from Fireheart, and kills him.
 * Also, Cloudpaw was taken away in the belly of a Monster.

Midnight

 * It is revealed that in the time between Firestar's Quest and this book, Sorrelpaw was hit by a monster, injuring her shoulder. However, it was not a permanent injury like Cinderpelt's; it only delayed her training for three moons, so she was made a warrior after her brothers Sootfur and Rainwhisker.
 * When Brambleclaw and Squirrelpaw are preparing to leave to find the Sun-Drown-Place, they sleep under a "sleeping" monster before they leave, to shelter from the rain.
 * The first monsters veer off the Thunderpath into the forest and begin ripping up dirt and trees, much to the surprise and fear of the warriors.

Moonrise

 * Many more monsters are seen in the forest as the Twolegs begin dominating the area. The prey is scared away by their presence, so the Clans struggle to find food in the harsh conditions.

Dawn

 * Monsters continue to tear up the forest.
 * Later, Shrewpaw gets hit and killed by a monster when chasing a pheasant onto the Thunderpath.
 * Graystripe is last seen being taken away in the back of a monster after saving Brightheart, Leafpaw, Mistyfoot, and several other cats from being trapped and taken away by the Twolegs.

Warrior's Refuge

 * Graystripe and Millie encounter a monster (car) on the Thunderpath by Husker's barn, and narrowly escape, and flee into a corn field. Unfortunately, another monster (corn harvester) cuts through the corn, separating the two cats.

Warrior's Return

 * Graystripe and Millie ride to the sea on the back of a monster (truck).

Bluestar's Prophecy

 * Bluefur's sister, Snowfur, is struck and killed by a monster while chasing ShadowClan invaders off ThunderClan territory.

Secrets of the Clans

 * Tawnypelt uses the word boat, showing that the Clan cats differ sailing boats from the monsters on the Thunderpath.