Katz is a red cat with thin limbs and a long body. He has yellow eyes with small pupils and purple highlights on the lower lids, as well as purple-tipped ears, a purple-tipped nose and three purple stripes across his back. Although he doesn't appear to have eyebrows, sometimes he does such as in his debut. He is a master of disguise and even dresses up to match the scam he's planning.
Katz is a smooth, callous and sadistic feline with a calm British accent and comes complete with his own sinister background theme music. Like most cats, he has a powerful distaste for dogs, however he reserves a special hatred for Courage. Since his debut, Katz's top priority has always been helping or advancing his situation in some way. He is competitive, as shown in Katz Kandy, where he tries to force Muriel to tell him her secret ingredient for her sweet recipes after coming in second place to her in the Nowhere Sweet Stuff Contest for years. Thus, crushing his competition is nothing new to Katz. Katz enjoys a few things, such as making confectionery treats, or managing his collection of spiders (which he refers to as his "loves").
He is quite the con artist, as well, specializing in scam businesses such as a vacation resort, a confectionery shop, a motel, and a submarine cruise line. It is shown that he often kills his customers: for example, he fed the residents of the Katz Motel to his spiders. Two of his common targets are, of course, Eustace and Muriel (who never seem to remember him from previous cons). Even if Muriel and Eustace are fooled by whatever service he is providing, Courage never falls for his schemes. Because of this, all of his businesses enforce a strict "No Dogs Allowed" policy, which forces Courage to have to sneak in to save his two owners.
Despite his sinister nature, Katz has always enjoyed a bit of pre-defeat "sport" with Courage, which he is quite apt at. It is common in some of these games that Katz will egg his opponent on into losing. For example, during the said staring contest, he kept saying "blink" when he saw Courage's eyes watering. In the end Katz can be classified as a pure psychopath, being very sadistic and deceptive, and having absolutely no regard for the lives of others. Katz shows clear signs of Antisocial Personality Disorder.
A Night at the Katz Motel
In his first appearance, he is running the Katz Motel. Eustace and Muriel get a room for the night. Because of the "No Dogs Allowed" policy, Courage is forced to be outside on the porch. It turns out that Katz runs the hotel to supply food for his collection of large man-eating spiders. He sends one out to get rid of Courage, while he captures Eustace and sneaks another spider into Muriel's bath. After escaping the spider sent out for him, Courage makes his way inside to save the old couple from being the spiders' dinner. Katz foils his attempts and challenges him to a dynamic game of racquetball. While Courage grows exhausted, Katz plays with almost no effort (even reading a book on spiders and enjoying a cup of tea). Though Courage loses and is held down by Katz, ready to kill him, he is knocked unconscious by Muriel with a racquet.
In his second appearance, Katz is running the exclusive Klub Katz on an island, where Eustace, Muriel, and Courage have washed ashore after a luxury cruise goes awry. The scheme this time is a club where the occupants get turned into half-machine versions of themselves to fight to the death in a coliseum for Katz's entertainment. He takes Muriel and Eustace to the spa, which of course has "No Dogs Allowed." When Courage sees Katz come out with his owners, Muriel and Eustace have been transformed into a washing machine and a wrecking ball, respectively matching their personalities-Eustace is always grumpy and destructive, while Muriel does a lot of work. Katz pits them both against each other in an abandoned colosseum where he runs a machine for applause while he watches from Eustace's chair (which he salvaged from the shipwreck). Courage goes into the spa to turn himself into a helicopter and rescues Muriel (with the help of a magnet) from the colosseum. Eustace, noticing Katz has his chair, takes a whack at the feline, only to destroy his chair when Katz dodges. He continues to chase Katz around trying to hit him, while Katz tries to reason with him.
Katz next appears in Katz Kandy. It is in this episode that Katz is shown to have his own candy store, Katz Kandy. The 43rd Annual Nowhere Sweet Stuff Contest is coming up, and he has won second place every year to Muriel, a fact that saddens and frustrates him. He whips up a jam monster to kidnap Muriel so he can get her to tell him her secret ingredient. Courage comes along for the ride, of course, with Eustace not far behind following (and eating) a jam trail left by the monster. While inside Katz's lair, Muriel refuses to willingly give him the secret to her recipes. He puts her on a candy cane over a taffy pulling machine and binds Courage with other taffy. Katz threatens Muriel to tell him her secret or he will pull the lever, which will lower her into the machine, which will pull her into a taffy and rip her apart. Fortunately, Courage manages to eat his way out of his binds and fight with Katz while back in the candy store, Eustace is beating the jam monster. Katz gets the upper hand in their bought though, and challenges Courage to a starring match when it becomes too easy for him to win. Courage holds up even with Katz egging him on to blink until Eustace enters the lair, effectively startling Courage enough to make him blink. Katz tosses Courage into a different machine that makes Courage into a candy cube. Katz goes back to the candy canes where now both Eustace and Muriel are and fights Eustace while hanging onto the candy cane trying to use his legs to pull Eustace down into the taffy machine (and vice versa). Courage rolls to the lever and the candy cane Katz is on goes down into the machine and Katz is pulled among the green taffy, still asking for the secret ingredient. Before they leave, Muriel tells him that if he must know, it's vinegar. Katz 'cheers' that it's vinegar. He makes it to the Sweet Stuff Contest, but he loses 1st place to Muriel yet again, and this time, he's his own entry, for he is shown as a green piece of taffy shaped akin to a hotdog wiener.
Katz Under the Sea
It seems Katz found a way to return himself back to normal by the time he is seen in Katz Under the Sea. In this scam, he is the captain of the SUB Standard Cruise submarine, the vacation submarine for those who feel overworked. Muriel, who is being overworked by Eustace, takes Courage there in need of a break. After appointing Muriel as his first mate for making tea, Katz says "No Dogs Allowed" and tosses Courage to the side (Courage, of course, stows away in another passenger's luggage). Courage masquerades as a ventriloquist doll, which fools Katz for enough time for Courage to figure out that Katz is planning to have the submarine blow up once they reach the bottom of the sea. Katz mistakes Muriel's complaints about the smell of the explosive 'Tea-N-Tea' for confirmation that she is a spy sent out to thwart his plans for blowing up the sub. He reveals that he plans to swim to safety while he ruins SUB Standards Inc.'s cruise so that his own Katz Submarine Cruise will get all the underwater vacation business. So once again, he is crushing his competition. Unable to find help, Courage tries to stop Katz, who is about to make his getaway, himself. Katz realizes he's a dog, and during their tumble, Courage breaks the lever that sets the course of the submarine on a collision course with the sea floor, much to Katz's joy. Katz escapes into the ocean, but then finds himself swallowed by a shark. While Courage manages to save everyone, Katz is left in the belly of the shark demanding to not be eaten.
Ball of Revenge
Katz apparently managed to get out of the shark no worse for wear, as he last appears in Ball of Revenge, along with all of the other villains whose various plans were foiled by Courage. Called to the farmhouse basement for a secret meeting by Eustace (who is jealous of Courage), he and the other villains make a plan with Eustace to get rid of Courage for good and have their revenge. Once they capture Muriel, she resists screaming (which is the bait to get Courage to come to her rescue). Katz begins his own brand of torture for her, by mixing the whites and colors in the washing machine and adding a ton of bleach as well. This effectively makes her scream, and Courage does race downstairs where he is jumped by the villains. Katz suggests a bit of sport before he slowly dies, which Courage is forced to accept. The game: Dodge ball. It's the villains against Courage, with Muriel and Eustace as spectators and Le Quack as the referee in Courage's last showdown with his enemies. Katz throws a ball with spikes at Courage, who evades getting hurt by it. Katz is then shocked and disgusted by the unrefined weremole, who eats his dodge ball. During the game, Katz helps his teammates, and pulls out a flamethrower when Courage is on his last legs and is about to lose. Muriel encourages Courage that there must be something he is good at, which gets him thinking. Then, sucking in much air, Courage does the thing Katz and all his foes have helped him perfect the entire series: his traditional scream. Courage screams so loud that the ground shakes, and Katz, along with all his teammates, fall into a hole created by the chasms of shaking ground that the scream made. It's unknown what becomes of him afterward, but he is presumed dead.
Profiles In Courage
- Katz is one of seven characters (the others being Courage, Eustace, Muriel, Shirley, Dr. Vindaloo, and the Computer) to appear in every season.
- Katz has a distinct theme song that tends to play in the background when he is around.
- The theme bares a resemblance to the Guantanamera theme from the movie Antz.
- He resembles Fergurina from John R. Dilworth's cartoon The Dirdy Birdy. However, unlike Katz, Fergurina is a girl.
- His psychopathy and well-mannered traits make him similar to Hannibal Lecter, the main antagonist from the film The Silence of the Lambs and its spinoff NBC show Hannibal, who is a serial killer.
- Unless one counts the Space Chicken (which appeared in the pilot episode), Katz is the first antagonist to appear on the show.
- He bears a resemblance to Swayzak from Toonami (another Cartoon Network franchise), both being lanky red antagonists with sociopathic traits (however Katz is way more of a sociopath than Swayzak, who only commits crimes for fun, and they act way different, with Katz being well-mannered and Swayzak being loud and over-the-top.)
- However, his line at the end of "Katz Under the Sea," "I am Captain Katz and I command you NOT TO EAT ME!" sounds not only out of character for someone like him, it also sounds like something Swayzak would say.
- "I wish you hadn't done that."
- "I'm sorry, no dogs allowed."
- "A little sport before dying, dear boy?"
- "Now you're going to learn why no one ever checks out of the Katz Motel."
- "My loves, dinner has arrived."
- "Sad, isn't it?"
- "I am Captain Katz and I command you NOT TO EAT ME!"
- "There's no place to run, and no place to hide."
- "Hmmm... how lovely..."