Cat is an elderly, anthropomorphic cat. He is taller than the other Knothole Freedom Fighters, and his tail is about half of his height in length. Cat's fur is dark brown; whilst his thick eyebrows and stomach fur are a faded blonde. He also has grey fur on either side of his muzzle and his eyes are olive. He also does not wear any form of clothes.
Cat eventually accompanied Sonic and Antoine on a mission to Robotropolis. After arriving in the city, they snuck through the air ducts and into the Stealthbot hangar. Meeting up with Sally there, Cat stayed behind with Antoine while Sonic went with Sally to sabotage the Stealthbots. After some time, however, Antoine mistakenly fell out of the air duct he and Cat were hiding in, thus catching the attention of the local Swat-Bots. After helping Sally get back into the air duct, Cat and Antoine began to run away with her. While fleeing however, Cat decided to separate himself from Sally and Antoine so he could lure the Swat-Bots away from his friends. His plan worked, but he was soon captured and brought before Dr. Robotnik, who wanted the location of Knothole Village from him. Cat, however, refused to talk, which led to him getting locked up in the detention center. Later, Sonic came to Cat to save him, but Cat told him to forget about him and go help Sally and Antoine, who were being followed by Dr. Robotnik's machines. Although Sonic ultimately agreed to Cat's decision when a band of Swat-Bots arrived, he promised that he would come back for him. However, by the time Sonic returned, Cat was no longer in his cell.
Cat is very loyal to his friends, ready to sacrifice himself for their own good. He also comes across as being calm, quiet, and not losing his head when faced with a difficult situation.