"But Firestar's claws struck their target, tearing at the throat of the rat at the center of the tide. He gazed into the small hate-filled eyes, and saw their hatred change to terror before the light faded from them. The rat's head dropped back and its body went limp."
The Rat Leader is an unnamed, manipulative brown rat that possesses the ability to speak in the language of cats (though, like Midnight, he does not possess the proper cat language). He is described as being bigger than most other rats, with a wiry, muscular body and curved yellow teeth.
When Firestar and Sandstorm are on patrol with some of the new SkyClancats, the rat leader appears. Firestar is surprised that the rat leader can speak cat, although it's noted that its words are twisted and odd. The rat leader informs the cats that the rats had killed SkyClan before and will kill them again. He and his group of rats attack SkyClan several times, but he prefers not to fight; instead, he chooses to give commands from inside the protection of a mass of rats. When the SkyClan cats begin to gain the upper hand in the battle, he orders the rats to retreat.
SkyClan attacks the rats' home in response to the rats' ambush on their camp. Firestar is uncertain what this means, but he decides that he needs to find the leader. Unable to tell which rat is the leader, Firestar tries to trick him into talking. He seems to know what Firestar is trying to get him to do, so he keeps silent as to not give himself away. After Firestar has told the SkyClan cats to retreat from battling the rats, Spottedleaf appears to him and hints that appearances are deceiving. Firestar then discovers that Spottedleaf means the mass of rats is taking commands from the leader through small movements, such as a twitch of the tail or brush of fur. Firestar traces the movements to the center of the pack and identifies the real rat leader. Swiftly, and without warning, Firestar kills him. Without their leader to guide them, the remaining rats flee.