Duke

Duke is a massive black-and-white tom with a spiked collar and nicks in his ears.

The Lost Warrior

 * Duke is a kittypet only mentioned in The Lost Warrior. He is noted to be very aggressive, and that he has never lost a fight. When Graystripe first goes out of his Twoleg's territory, he meets Duke, taunts him, and Duke begins battling him. However, Graystripe is weak from being kept in the Twoleg nest so long, and loses the fight. This makes him think if he still truly a warrior or if he is turning into a kittypet. Later, when Graystripe is training Millie to be a warrior in the clearing in the small forest by the Twoleg Place, Duke comes in with his two other kittypet companions and tells the two to leave saying that it is his clearing even if he hardly goes there, thus starting another fight. This time, training with Millie has strengthened Graystripe, and he and Millie win. Duke runs off, calling Graystripe a savage. He is not seen again.