Woollytail is a gray-and-white tom with bright yellow eyes and wide shoulders.
Woollytail is known to be one of the best tunnelers in WindClan, and Sandgorse's closest friend. He is a hard worker, and leads the project on creating a tunnel to the gorge, demonstrating his knowledge about the inner workings of the tunnels and how to avoid cave-ins while reinforcing it at the same time.
It is known that Woollytail complains about the lack of tunnelers, so when Stagkit, Ryekit, and Doekit are apprenticed, the WindClan cats assume Woollytail will mentor one of them. However, they are all apprenticed to moor-runners, leaving the tunnelers annoyed. Woollytail asks Heatherstar why they were not informed that the tunnelers would not be getting apprentices, and although unhappy with his leader's decision, he does not question it.
As Tallkit's time to be apprenticed nears, the tunnelers are certain that he will be apprenticed to Woollytail, as Tallkit's father was a tunneler. Much to the tunnelers' surprise, Tallkit is apprenticed to Dawnstripe, infuriating Woollytail and Sandgorse. Woollytail argues with Heatherstar on her decision, but Heatherstar does not budge.
As part of his apprentice training, Tallpaw is offered to visit the gorge tunnel, but it floods, greatly frightening the young apprentice. Dawnstripe hears about this, and takes Woollytail to WindClan's camp to tell Heatherstar. Heatherstar therefore bans all work on the gorge tunnel, adding to the tunnelers' anger. Although Woollytail does not blame Tallpaw, he is solely disappointed for the loss of work.
Sandgorse is killed by a cave in, and when Tallpaw tries to avenge his father by taking up tunneling, Woollytail rescues him from the tunnel caving in on him. Tallpaw decides to train as a tunneler, and the news delights Woollytail, but he urges him to not try and do what Sandgorse wanted of him. Woollytail does not get a chance to train Tallpaw, as Heatherstar, hearing of Sandgorse's death, bans tunneling for good.
Woollytail spends more and more time with Palebird, Tallpaw's mother. Tallpaw pays attention to this, and is not surprised when Woollytail tells him that he will soon be a brother. Tallpaw reminds Woollytail that Sandgorse was his closest friend, and Woollytail replies that he would have wanted Palebird to be happy, as she had not been happy in a long time. He begs Tallpaw to understand, but Tallpaw can only walk away.
Palebird gives birth to Woollytail's kits, Flykit, Wrenkit, Rabbitkit, and Brislekit. Talltail is still annoyed at Palebird's choice to start a life with Woollytail and move on from Sandgorse, leading Woollytail to chide him.
Some time later, Woollytail dies. He is seen at Talltail's leader ceremony, and gives him a life for honoring the old traditions that create the foundation for future WindClan cats.