Duke

The Lost Warrior
Duke is a kittypet only mentioned in The Lost Warrior. When Graystripe first goes out of his Twoleg's Territory, he meets Duke, taunts him, and starts a fight. However, Graystripe is weak from being kept up so long, and loses the fight. Later, when Graystripe is training Millie to be a warrior, Duke comes in with his buddies and starts another fight. This time, training with Millie has strengthen Graystripe, and he and Mille win. Duke runs off and is never heard from again.