|Occupation||Inventor and assistant to Motherboard|
|Allies||Motherboard, Digit, Ada Lovelace, The Cybersquad|
|Voice actor||Richard Binsley|
Dr. Marbles is a brilliant inventor who assists Motherboard, and is trying to restore her to her full power. He is always full of ideas and helps out the Cybersquad. In his solo quests to assist Motherboard, he usually doesn't get to finish them because of The Hacker, whom he created as an assistant to Motherboard originally. He is usually called "The Doc" by Digit, due to their partnership and friendship.
Dr. Marbles first appears in the very first episode, "Lost My Marbles".
Dr. Marbles has lavender skin, a blue mustache and eyebrows, yellow eyes, red glasses, and what appears to be a light bulb for a head that flashes red when there is danger nearby (Clock Like An Egyptian). Dr. Marbles wears a light blue jacket with dark blue at the collar and wrists. His pants are blue but his boots are black. In "The CyberChase Movie", parts I and II, he has a long blue beard.
His favorite book is Zen and the Art of Motorcycle Maintenance by Robert M. Pirsig and his favorite movie is Tron. He has a love interest in a female computer programmer named Lady Ada Lovelace as shown in "Hugs and Witches".
Issues with Hacker
After Hacker removed the Encryptor Chip from Motherboard, Dr. Marbles had the opportunity to permanently delete him, but chose instead to take away his power supply and banish him to the Northern Frontier. Because of this, Hacker needs to regularly recharge himself with his recharger chair. Therefore, it is possible that Hacker hates Dr. Marbles more than anyone else. Some of Hacker's earliest schemes have involved attacking him personally, making him his prisoner, and using him to his advantage such as in "Castleblanca" when he tried to use Marbles' brain power to activate Gigabyte. In "Step by Step ", Hacker reminds Dr. Marbles that when he first built him, he gave him brain power equal to his, which is evident as to how Hacker is such a formidable foe towards him. Overall, what started as a seemingly good relationship, as assumed in the flashback in "A Piece of the Action ", has become nothing more than a bitter struggle between creator and creation.
- Dr. Marbles usually speaks in computer jargon such as "Backspace!" instead of saying "Hold on!", "Your file is closed!" instead of "You're finished!" and "We must exit this program!" instead of saying "we must leave this place!"
- Originally considered a main character, Dr. Marbles began to appear less and less in the series until eventually disappearing from the later seasons with the exception of Episode 605.
- Doctor Marbles has an unknown sister and brother-in-law, because he has a nephew: Sleight O' Hand, Cyberspace's most famous pickpocket seen in The Guilty Party.
- "Lost My Marbles" (First Appearance)
- "Clock Like an Egyptian"
- "The Secrets of Symmetria"
- "A Day at the Spa" (Flashback)
- "Trading Places"
- "Less Than Zero"
- "Hugs and Witches"
- "All the Right Angles"
- "A Piece of the Action" (Flashback)
- "The Snelfu Snafu: Part 1"
- "The Snelfu Snafu: Part 2"
- "Step by Step"
- "The Cyberchase Movie"
- "Housewarming Party"