Sharptooth is mentioned to be a lion-cat (mountain lion), living in a cave near the Tribe of Rushing Water, preying on the Tribe cats. He is greatly feared by the Tribe, and cave-guards are assigned to go with hunting groups to watch out for him.
Stoneteller receives a prophecy that a silver cat would come and save them from Sharptooth. He tells this to the Tribe, saying that all they can do is wait for the silver cat to arrive, and to not lose hope.
When Brambleclaw, Squirrelflight, Stormfur, Tawnypelt, Crowpaw, and Feathertail arrive at the Tribe's home, they realize that the Tribe seems to be afraid of something, which is later confirmed to be Sharptooth after Stormfur sights the mountain lion. The Clan cats, eager to return home, attempt to leave, but Stoneteller tells them that Stormfur can't, because he is prophesied to defeat Sharptooth. The other Clan cats try to help Stormfur escape, but Sharptooth enters the cave, allowing them to rescue him during the commotion. As they leave with Stormfur, they see Sharptooth leaving with Star in his jaws.
While the Clan cats are on the run, they get lost and enter a cave, stumbling upon Bird, Rock, and Talon, who are former Tribe cats. The three loners tell the Clan cats how the Tribe of Endless Hunting chose six cats, including themselves, to go and kill Sharptooth. They failed, and three cats were killed, leaving just Bird, Rock, and Talon. However, the surviving cats could not go back to the Tribe while Sharptooth was still alive, because it was the will of their ancestors for them to defeat him, so they now live as loners in a cave. Stormfur, who is now starting to think that he in fact is the silver cat, knows he must return to the Tribe and kill Sharptooth, which they all agree on. When they wonder how to kill him, Squirrelpaw says that if they themselves can't kill Sharptooth, then something else can.
The Clan cats return to the Tribe, and it is revealed that Sharptooth killed two cats and severely injured two others. Talon, Rock, and Bird also return, saying they want to help, which Stoneteller allows. Squirrelpaw says that the plan is to stuff a dead hare with deathberries for Sharptooth to eat, and they all start preparing. While the Clan cats stuff the hare, Talon cuts his paw to leave a blood trail as bait. Sharptooth follows the trail and comes, however, he doesn't eat the hare and instead goes for the cats. Squirrelpaw, coming out of hiding, tries to distract him, but Sharptooth goes for Crowpaw, who couldn't hide in time. Seeing this, Feathertail reveals to Stormfur that she is the silver cat, as she has heard voices saying this is for her to do. She leaps up to the roof of the cave, sending stalactites down on the mountain lion, killing him instantly, though also dying in the process. The Clan cats mourn her while the Tribe celebrates Sharptooth's death.
After the badger attack on ThunderClan'scamp, Brook mentions that she had seen that kind of savagery before, when Sharptooth was terrorizing the Tribe cats. He is also mentioned again as the cats are thanking Midnight, the badger, for bringing WindClan to help, and Brook asks why the other badgers attacked, and if they wanted to kill cats for prey, just as Sharptooth once did.
As he speaks with Stoneteller, Jayfeather comments that the Tribe had to be given a chance to survive, and it would be easy to give up the first time something went wrong, and Stoneteller replies that it was not the first time, and inquires if he had forgotten how many of the Tribe was hunted like prey by Sharptooth.
In "Stoneteller Speaks: The Coming of the Silver Cat", Sharptooth is mentioned by Stoneteller, who is anxious about the mountain lion because he is killing many Tribe cats. Stoneteller receives an omen that a silver cat will defeat Sharptooth, and thinks Stormfur is the silver cat. He also notes that Feathertail's coat is silver, but still believes that Stormfur will save the Tribe. Stoneteller then pleads with the Tribe of Endless Hunting to help the silver cat defeat Sharptooth.
He appears on Crowfeather's page. The Tribe of Rushing Water were plagued by a mountain lion named Sharptooth. The Clan cats laid a trail to catch Sharptooth and feed him prey stuffed with deathberries, but Sharptooth arrived too soon and Crowpaw became trapped behind a corner of the cave. Feathertail leaped up to a talon of stone that hung from the roof. She wrenched it free, plunging it down into Sharptooth’s back, killing him instantly.
He briefly appears on Feathertail's page. The Tribe of Endless Hunting foresaw that a silver cat would save the Tribe of Rushing Water from Sharptooth, a mountains lion that preyed on them and the prophecy from the Tribe's ancestors came true. It is also mentioned on the Tribe’s Introductory page that the Tribe found themselves helpless after Sharptooth came, waiting for a silver cat to come.
He appears on Teller of the Pointed Stones' page. Stoneteller had to face the cruellest enemy of all: Sharptooth, who seemed determined to treat every cat as prey. When a party of sent out to kill Sharptooth never return to their tribe, Stoneteller began to despair. The Tribe of Endless Hunting sent a prophecy that a silver cat would save them from Sharptooth but Stormfur's battle tactics failed against another attack from Sharptooth failed. Stoneteller was resigned to watch his Tribe perish in Sharptooth's jaws, until this time, Feathertail succeeded in killing Sharptooth.
He is lastly mentioned on Brook Where Small Fish Swim's and Stormfur's page. When Brook first met the Clan cats, she wondered if Stormfur is the prophesied cat to save the Tribe from Sharptooth.
In A Forest Divided, it is revealed that Sharptooth is the term for giant cats living in the mountains. Sharptooth is the only known giant cat encountered by the Tribe of Rushing Water, although they are mentioned to be very rarely encountered.
In Secrets of the Clans, Crowfeather mistakenly called him Sharpclaw when he was referring to Feathertail's death in "Crowfeather Speaks: A Forbidden Love."