April O’Neil is a young human woman who has appeared in almost every version of the Teenage Mutant Ninja Turtles franchise. April is usually the Ninja Turtles‘ first human ally in most incarnations, and is generally portrayed as a news reporter and a very good friend of the Ninja Turtles: Leonardo, Donatello, Raphael, and Michelangelo, often acting like a big sister or surrogate mother to them. April’s love interest in the franchise is often at Casey Jones, who is also a close friend and human ally of the Turtles.
Cat is the smarter, more clever and more cunning of the two. He often devises plans to trick Dog into getting what he wants, such as making Dog smarter in an attempt to have more in common with him, or having him win a dog sledding contest by training him in a very hard and militaristic manner, and usually, as a result of his greediness and selfishness, these schemes all blow up in his face. He is the “underdog” of the two. Life has been hard for the both of them, as they have been shunned by society due to their awkward appearance, but Cat always seems to get the short end of the stick in the situations, especially faced with the Greaser Dogs. With his brains and constant ridiculing from the rest of the characters, he’s the more defensive and short tempered of the two. Despite his quirks and spats with Dog, he loves his brother with his whole heart. He cares so deeply that he ends up helping Dog in the end once his guilty conscience gets to him. Cat has a “Crush” on Shriek. In one episode Cat admits his love for Shriek and kisses her after Shriek kisses Dog and tells him she loves him.
Cat desires fame and fortune, and tends to go to excessive lengths in order to gain them. He is intelligent and enjoys reading, gardening, and listening to classical music. Cat is somewhat uptight and believes strongly in being polite and neat. He is a stickler for cleanliness and, like most cats, is aquaphobic. He is also obsessed with jet skis, once stating that he would sell his soul for one. Cat is 26 years old. Cat’s catchphrase is “Terrific,” said in a negative tone, as he usually says it when something bad happens.
Dog is the more happy-go-lucky and more naïve of the two. He is also the source of clumsiness. He is extremely ambitious when Cat or any other character convinces him to take on a task, diving right into it with full force and energy. Dog is the typical loyal “dumb dog” and is easily convinced. He will believe everything he is told. His attention span is very short and he is easily distracted by balls, garbage trucks, bones, food, and his overactive imagination. Because of his more simple nature, Dog usually is the one who gets the pair into trouble. Not paying attention to Cat’s warnings, his actions almost always end up with some severe consequences. Despite this, in many of the episodes, it is shown that Dog is usually the one that is more popular and athletic of the two, such as the episode when Cat and Dog both went back to school to complete Cat’s last day of High School. Like Cat, Dog adores his brother and looks up to him no matter how many times Cat steers him into danger. Dog is the typical animal. He is often distracted with chasing shadows and chasing after tennis balls, and loves eating garbage. Much to Cat’s dismay, he leaves a mess everywhere he goes. According to the series finale, Dog remembers what their parents were like.
Dog’s catchphrase is “Hi ho diggety!”, which he usually says when he is excited about something.