The cat seems to be linked to Claw's personality, as whenever claw is happy MAD Cat will purr, but whenever he is mad he will hiss and yowl and this is his signature sound at the end of every episode. After Dr Claw says "I'll Get you next time Gadget. Next time." MAD Cats yowls. In the series his breed is unknown, but in the film he is a white persian like Mr. Tinkles.
In Gadget and the Gadgetinis MAD Cat has the same role as first series but different colour because it is bluish black.
In the 2015 series MAD Cat has the same role and colour as first series (with the only difference that is female). However, in this series she has a bigger and independent bad role in episode "Back to the MAD future" (a clear parody episode to Back to the future trilogy), where Inspector Gadget, Penny and Brain has to travel to the past for evit that Talon gave his uncle past a disc with the information about the greatest evil plans in the actual age. When Talon is going to give to his uncle past the information, Gadget, Penny, Brain and Gadget past bring in action but Brain falls into a MAD suit past and two Gadgets chase him. During battle between them, and Penny and Talon, both sides accidentally activate a bomb in teddy bear form, forcing them to flee and the lair blows away.
Current Gadget & Co returns to their age and Gadget past to his home thinking that the information has been destroyed. Talon returns to his age after telling his uncle past ascended him in his future criminal life but Claw past is sad because, to see the lair destroyed by the explosion he thinks that baby MAD Cat, his only friend, has dead, and believes that crime isn't important, so is redeemed. But it results baby MAD Cat has survived to explosion and has the intact disc. When Gadget & Co is back to their age, they see a completely different world where Doctor Claw is Police chief, Quimby is his lieutenant and, even worse, MAD Cat rules driving a giant feline robot and wears the Alter-ego "MAD Cat Mech". As misfortune for Talon, he's only her own slave instead of his righ-hand, like alternate Dr. Claw.
Gadget & Co are persecuted by MAD Cat Mech, who tries to destroy them, through time until finish in the past after the last visit. Dr. Claw past is meditating to be a good guy and, when Gadget & Co arrives, Penny tries to convince him to being a bad guy again but Claw doesn't listen. Amid discussion, MAD Cat Mech arrives with her slave and explodes a terrific fight in which even same Gadget past engages, interrupting Claw's meditation and turning him bad again. In this manner, MAD Cat Mech is wiped out of existence and reality is restored.