Katz

"I wish you hadn't done that."

- Katz's catchphrase.

Katz is the most recurring villain in the Cartoon Network series Courage the Cowardly Dog. He is a red anthropomorphic cat who is Courage's arch-nemesis and the show's main antagonist.

He was voiced by Paul Schoeffler.

Personality
The main humor in his role is that Katz appears so much more than Courage; he is athletic, intelligent, manipulative, cunning, and more sly than Courage. However, Katz is cruel, sadistic, and destructive. He specializes in scam businesses such as a vacation resort, a confectionery shop, a motel, and a submarine cruise line, always with the intent to kill the patrons when he has no further need for them.

Role
He always cons Muriel and Eustace as he did with most other people into trying whatever service he is providing, but Courage never falls for his schemes. All of his businesses enforce a strict "No Dogs Allowed" policy, forcing Courage to sneak in. He always enjoys a "little sport", as all of his battles with Courage are games such as a staring contest. His catchphrase (typically uttered whenever he gets injured) is "I wish you hadn't done that.".

A Night at the Katz Motel
He makes his first appearence in the first episode of season 1 ''A Night at the Katz Motel. ''When Eustace, Muriel and Courage are returning home from their vacation they stumble upon the Katz Motel and go inside to stay for the night. Then they meet Katz at the counter. He asks them to sign their names on a sheet of paper but then stops after seeing Courage. He points to a sign which reads No Dogs Allowed. Distraught, Courage is taken outside to stay. As Eustace and Muriel settle themselves in, Katz opens the door behind him, revealing a giant web housing large spiders. He tells them that their dinner has arrived, as he was referring to the humans and Courage. He then walks away after telling the spiders to clean their web, due to how filthy it is. Katz watches over Eustace as he is sleeping and watches Muriel from the tap as she's bathing. He then lets out a spider into the bathtub to eat her. Meanwhile, Courage is sitting outside mopingly until he catches a glimpse of Katz' shadow. Katz' arms reach out from behind a corner and he places down a small wooden box and opens up the lid, thus letting out a spider to eat Courage. Luckily, Courage escapes and is safe, but not until he finds Eustace tied up in a web about to be eaten by a giant spider. Katz closes the door behind Courage asking "Leaving so soon?". Courage then picks up Eustace and throws his body at Katz knocking him down, with Katz uttering "I wish you hadn't done that".

Courage runs out of the room being chased by Katz. After rescuing Muriel from the spider, Courage runs into another room to escape from Katz, but Katz corners him. Trapped and having nowhere else to go, Courage expects Katz to kill him straight away, but instead Katz offers him a quick ball game before he kills Courage. Whle playing, Katz reads a book about spiders and drinks a cup of tea. After beating Courage, Katz grabs his neck saying "Now you'll know why no one ever checks out of Katz Motel", and raises up a spider which he prepares to kill Courage with, while at the same time laughing maniacally. However just before Katz kills him, Muriel whacks him over the head with a tennis racket, knocking the feline straight out and falling on the floor.

Klub Katz
His next appearance was in Klub Katz. This time, we see Katz running the exclusive Klub Katz on an island, where Eustace, Muriel, and Courage are washed ashore after a luxury cruise goes awry. 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, arrogant, and destructive, while Muriel does a lot of work. Katz pits them both against each other in an abandoned coliseum 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 coliseum. 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 suggest therapy and reason in vain. The episode is a spoof of The Island of Doctor Moreau, in which a sinister vivisectionist turns humans into half-animal creatures.

Katz Kandy
The third time one sees Katz is in the episode 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. 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 not to 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 big show down 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 flame thrower 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: 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 remains unknown if Katz and the other villains survived since they never return after the final battle.

Quotes
"Ready for a little sport before slow dying, dear boy?"

- Katz

"Leaving so soon? (Courage: OOOOOOOOOOOO!) There is no place to run! And no place to hide! Now you're going to learn why no one ever checks out of the cats motel! Hahahahaahahaha! Huhuhuhuhuha! Hihihihihihha! Bahahahaha!"

- Katz torturing Courage and showing his sinister laughter.

"I'm sorry, no dogs allowed."

Trivia

 * He is considered one of the darker villains in the cartoon, but when thinking about the other characters in the cartoon, like King Ramses, The Mask, Violin Girl, Freaky Fred, and The Blue "You're not perfect" creature, he really isn't that horrible.
 * There is a fan theory that the reason the cartoon is so dark is that it is focused on how Courage sees the world, and how the world is structured in his mind, and Katz isn't one person, but symbolizes some strange humans that Courage meets. But this fan theory is easily debunked considering the directors stated themselves why it's so dark is because it is a parody on Gothic Horror.
 * Even though having so many dark villains in the cartoon, Katz is the only villain to be Pure Evil.
 * He is similar to Bill Cipher from Gravity Falls:
 * Both are known for their trickery
 * Both are the darker villains of their cartoon
 * Both come from cartoons
 * He is similar to Drago Bludvist from How to train your Dragon 2:
 * Both are Pure Evil
 * Both are extremely cold and have very little sense of humor if any
 * Both are the darker of their respective series