Dukey is Johnny's dog and best friend. He is the deuteragonist of Johnny Test franchise. One of the most notable things about him is that he has the ability to speak. He was a very disgusting dog until Susan and Mary enhanced him. Since then, he can both fetch the paper and read it. He is also a master at karate, knows somewhat how to speak Chow Mein, play video games and gives great advice. When Johnny, Susan, Mary and Dukey are near a human that does not know Dukey and he (Dukey) talks, the other person usually says "Did that dog just talk?". Or when Dukey is near Johnny's dad, and Dukey talks, he (Johnny's dad) says "Did Dukey just talk?".
He is often the voice of reason to Johnny's insanity, but winds up getting manipulated into supporting Johnny's crazy schemes and adventures (usually because of steak or Johnny tempting him into it). Despite his devotion to Johnny, Dukey frequently expresses deep disdain towards Johnny's less intelligent antics, believing their situation as master and pet is reversed.
His dog habits greatly annoy Johnny's sisters, to which Johnny takes deep delight in. Usually once per episode, when trouble arises and there's no alternative, Dukey will say something along the lines of "Here's an idea: RUN!" Similar to Johnny's "Johnny X" form, Dukey also has a secret identity which unlike his master he does not particularly enjoy called "Super Pooch", although he is also referred to as "Super Dukey" and "X-Pooch". When in "Super Pooch" form, Dukey can fly and in the Third Season has shape shifting powers, the ability to sense what others are doing, and the ability to teleport. He has the power to fly as a sidekick (to Johnny) but usually crashes when landing. He also likes to drink hot coffee. His favorite food is steak (He likes all kinds of steak, but his favorite is porterhouse seen when Dukey quizzes Johnny and his cyborg clone to see who's the real Johnny.