The Kin is a group in the Vision of Shadows arc of Warriors. It was lead by Darktail.
Darktail and the rest of his group came to SkyClan. Eventually overpowering the fragile Clan, they took over the gorge and scattered the cats of SkyClan into the Twolegplace and the rest of the forest surrounding the area.
StarClan telling then-named Alderpaw that SkyClan was in trouble, he took a group of cats on a journey to the gorge, only to find the Kin residing there instead. Thinking that the aggressive cats were SkyClan, Alderpaw tried to help them, before finding out that the cats did not believe in the warrior code or StarClan. Alderpaw then met Mistfeather who revealed that they were in fact invaders that had taken over. The Kin, upon noticing this, barred Alderpaw and his group from leaving the gorge and held them prisoner until they finally escaped.