Catnip is a character who appears exclusively in the animated television series Hello Kitty's Furry Tale Theater. She is a female cat and the daughter of another character named Fangora. Physically, Catnip is depicted as a tall Siamese cat with distinctive green fur. Her facial features include yellow eyes with noticeable eyelashes and blue eyelids, and she wears a jeweled collar around her neck, which features a diamond-shaped jewel hanging from its front.

In terms of personality, Catnip is consistently portrayed as a diva-like and envious individual, and she frequently takes on the role of the antagonist in the various plays and stories the characters perform. Despite this tendency toward villainous roles, she is shown to be sociable and can display a friendly side toward the other characters. Her behavior suggests a complexity to her nature; for instance, in the episode Catula, she secretly gives My Melody a spare carton of milk after an accident and explicitly asks not to be thanked or mentioned, stating she does not want to ruin her reputation. This moment implies that Catnip may deliberately choose to play antagonistic parts because she believes others already see her in that light, or perhaps because she has embraced a reputation as a villain. Her motivations often center on maintaining this diva persona, and she shows a desire for attention and status. In the episode Cinderkitty, she plays the role of a stepsister who is rude and careless, and her character hopes to be chosen as the prince's princess, showcasing her envy and ambition.

Within the story structure of Hello Kitty's Furry Tale Theater, the core cast presents theatrical productions of classic tales, and Catnip is a key member of this repertory company. Her primary role is to act as the main antagonist or a secondary antagonist in a vast majority of these performances. Her notable antagonistic roles include the Wicked Witchy of the West in The Wizard of Paws, Sultaness Catnip in Grinder Genie and the Magic Lamp, Scroogenip in The Year Scroogenip Swiped Christmas, Catula in Catula, Morgan Le Fur in Paws of the Round Table, Frankencat in Frankencat, Darth Catnip in Cat Wars, and Captain Claw in Peter Penguin, among many others. In some stories, however, such as The Ugly Quackling and Kitty and the Beast, she plays non-antagonistic roles.

Catnip’s key relationships within the theater troupe are particularly notable with Grinder. She is frequently associated with him, often trying to boss him around and push him to do her bidding, though he is typically depicted as dim-witted and struggling to understand her commands. This dynamic often casts them as a villainous duo, with Grinder serving as her bumbling accomplice. Her mother, Fangora, is another character who sometimes performs in the theater, often taking on the role of a secondary antagonist as well. Her relationships with the more heroic characters, such as Hello Kitty and My Melody, are generally polite and collegial off-stage, despite the conflicts she instigates during their plays.

There are hints of development or hidden depth in Catnip’s character. The moment in Catula where she performs a kind act anonymously suggests a more vulnerable or generous side that she consciously chooses to hide to protect her tough, villainous image. This is further supported by the line her character speaks as Scroogenip about never having received a gift, which a source speculates may be as true for Catnip herself as it is for the character she is playing, implying a possible underlying sadness or loneliness that informs her prickly exterior. As for abilities, while no explicit superhuman powers are detailed, Catnip is a capable and versatile actress, which is her primary function in the series. She consistently performs leading villainous roles and demonstrates a strong stage presence. Her ability to command and manipulate Grinder, though often unsuccessful due to his incompetence, also functions as a key trait.