Athos, known as Stone Shaper among the treecats, was a treecat on Sphinx and member of the Bright Water Clan.
He was "among the finest flint shapers in generations" in the clan. Lionheart received a knife made by Athos when Lionheart became a scout for the clan. (SK4)
He was mated with Golden Eye and was afflicted with the gray death following Golden Eye's death, which caused treecats to lose their mind-voice. After losing his mind-voice, he gave himself the name Stone and moved away from his clan because he knew the other treecats felt uncomfortable around him. He lived near a human settlement and regularly scavenged food and equipment from it. He used the scavenged goods to build a very warm nest.
He helped rescue Cordelia Schardt-Cordova after she injured her ankle running from a swarm of near-weasels. He was given the name "Athos" by Cordelia, after one of the Three Musketeers. (SK4)