The Greaser Dogs are a gang consisting of three dogs named Cliff, Shriek and Lube. They serve as the main antagonists of the series, CatDog. They live in an alley of Nearburg with a graffiti of CatDog on a brick wall, and they are often seen punching the Cat in the CatDog graffiti on a trash can in front of Lube (they sometimes live in a dog house with Shriek's separate dog house attached to it with chains in some episodes). They act no differently than school playground bullies, picking on anyone either weaker or different than them, usually by attacking them in a way that they refer to as pounding. Cliff is the leader of the Greasers. They physically bully CatDog (mostly Cat) whenever they see them, and they usually refer to them as CatButt because Dog, in some episodes, has Cat for a rear end. Apparently, they blow punches to Cat more than Dog due to Shriek declaring that she will not hit Dog. Dog once wanted to join the Greasers because he is also a canine, according to "Full Moon Fever." They bully CatDog just because they are different as revealed in the first episode, "Dog Gone." The Greaser Dogs also have a fear of a tick, which usually renders them helpless in almost any situation. The Greasers also have the fear in what Cat or Dog is capable of doing (in Monster Truck Folly, Cat revealed his dark side and punched the Greaser Dogs' monster truck in a monster truck arena, and in Pumped, Dog drank too much Choco Muscle energy drinks, his body transformed into a bodybuilder, and he destroyed the Greasers Dogs' home. Forunately, Dog was sorry for all of the damage he has done). The only way that they could succeed is to cause pain. The Greasers somehow never gets arrested for beating up CatDog since Rancid Rabbit tolerates it (only arrested in episode CatDog Catcher for not having a dog license). However, they sometimes teamwork with Rancid Rabbit, such as the episode where Rancid Rabbit is so jealous that everyone buys CatDog Candy and no one buys his candy anymore, so he hired the Greasers to demolish the CatDog Candy factory, hence Rancid also hates CatDog. Despite this, the Greasers also hate Rancid.
Cliff: (voiced by Tom Kenny) The leader of the Greasers who is a deformed dog. He wears a black jacket with a picture of a cat on the back of it. He is very short tempered and speaks with a gruff Brooklyn accent similar to Winslow. In "Squirrel Dog," Eddie was accidentally glued to his jacket which them turned into "Squirrel Dog," as a result of getting a taste of his own medicine as Shriek and Lube kicked him out of the Greasers because he was a "two-faced freak." However, once he was free from Eddie, he returned to his old bullying ways and rejoined the Greasers. In another episode, "Beware of Cliff", he made a solemn vow to never bully anyone again, but it didn't last long. In one episode, CatDog were laughing at Cliff most of the time because they were hallucinating Cliff as a ballet. Cliff has the same voice actor as Dog.Shriek: (voiced by Maria Bamford) The only girl in the Greasers. She is a tiny poodle with a squeaky, raspy voice. Though she's as tough and loyal as the other two, she's very emotional romantically and has a huge crush on Dog (though he never appears to notice) and frequently tries to hide it from the other Greasers. In "Shriek Loves Dog," her secret crush was unveiled. Shriek declares that she'll never hit Dog, she'll only hit Cat. However, she does get along with Cat sometimes. In the episode "Rich Shriek Poor Shriek", she came from a rich family, but she didn't like the posh life, so she left home and become a greaser. She pointed out to Cliff and Lube that she's actually a girl in which both Greasers finally realized it and screamed.
Lube: (voiced by Carlos Alazraqui) A hound dog, and the slowest and sweetest one of the group. He'll forget what he's saying and slur his speech. Despite this, however, he can speak perfect Spanish. He's the most loyal of the three Greasers. Despite his dull wit, like his parents, Lube has lots of musical talent and can sing very well. It is important to note a character design modification that occurred after the first episode; in the premiere episode "Dog Gone", Lube appeared with black dot eyes and long brown hair that extended down to his nose. In subsequent episodes, his appearance was changed and remained that way until the end of the series. In one episode he rolls up his right trouser and takes off a wooden leg. He also works part-time as a mechanic. His parents, a cat mother and a dog father, appeared in the series finale and said that Lube got separated from them a long time ago.
- The Greasers pose similarities to several troublesome trios. They are like the Kanker Sisters as all three trios usually get away with their crimes.
- They are similar to Shenzi, Banzai and Ed of The Lion King as both canine trios have two boys and one girl. Also, both Lube and Ed are stupid.
- They are also similar to Team Rocket from Pokémon despite rarely being blasted up high into the sky if defeated.
- They are similar to Yakko, Wakko, and Dot from Animaniacs because they also have two boys and one girl. However, the Greasers love to chase CatDog, whereas Yakko, Wakko, and Dot do silly stuff.
See The Greaser Dogs/Gallery. (Unfinished)