Although The Venture Bros. is a parody of Jonny Quest, some Jonny Quest characters appear in several episodes. This is due to the fact that Cartoon Network owns the rights to the Jonny Quest characters. Some of these characters, particularly Action Johnny, are drawn with variable line weights in the same style as the original comic-book-like Jonny Quest cartoons, as a visual homage.
Action Johnny (voiced by Brendon Small): Since the death of Dr. Benton Quest, he has been secreted away within the Quest Bathysphere, feeding (when possible) his addiction to narcotics, as shown in the episode “Twenty Years to Midnight”. He is fooled into handing over a piece of Dr. Venture Sr.’s machinery after being bribed by the Captain and Jonas Jr., an act that Jonas Jr. later resented. He has sobered up, but is still a high strung nervous wreck due to his many psychological issues resulting from his father,. In “The Buddy System”, Johnny claims that “fathers are caring and protective men, and I don’t have one of those”. In the same episode, Johnny also expresses the want to free Dean from his father, but is stopped mid sentence by Brock. He has since shown to become much better in Self Medication as well as more functional.
Race Bannon: Brock’s friend from the Office of Secret Intelligence, where he once worked as a torturer. Died after jumping from a jet that Nat King Cobra’s Snake Men were piloting while retrieving the Goliath Serum. He carries various spy gadgets (all of them extremely dangerous) that are reminiscent of those carried by James Bond.
Rajni Singh: See Hadji Singh. Another former Jonny Quest character, he is now a manager working with Jonas Jr. He is seen also taking care of Johnny, while worrying that if he brings Johnny back home, his (Hadji’s) wife will leave him.
Dr. Zin: A recurring Villain in the Jonny Quest series, was featured in the episode “The Buddy System” in which he was to be a special guest star in a stage show featuring Action Johnny. The show was being performed as part of “Rusty’s Day Camp for Boy Adventurers.” Upon seeing his old nemesis, Johnny panics and runs away in fear. Sergeant Hatred, having interrupted the show with what he thought was a routine arching, greets Zin with a hand shake, saying “The Dr. Z! Aw man, I love your work.” In “Self-Medication” Dr. Zin was confronted by Action Johnny, Dr. Venture and a group of former “Boy Adventurers” for accusing him as the murderer of their therapist. However, Dr. Z is innocent and the group discover that he is married. During a peaceful dinner Dr. Z advise the former “Boy Adventurers” that they need to grow up and to stop living in the past.