Dexter's caged pet monkey.
When off duty, his personality is similar to Dee Dee's and he is often seen playing with her in the laboratory, but when it is time to save the world Monkey extremely serious and heroic and risks his very life to ensure the safety of the world and those he loves. He is often paired with his sidekick and girlfriend Agent Honeydew on his missions who he cares about deeply and appears to posses a psychic link with her.
Monkey has the ability to fly, use super strength, and shoot lasers. Working for a secret global agency, Monkey protects the world from intergalactic villains, large monsters, and natural disasters. He also has his own arch-nemesis (who is a female duckling) called Quackor, who is owned by Dexter's arch-nemesis,Mandark and is the only villain to have ever managed to nearly beat Monkey in combat.
- Monkey's voice actor is Frank Welker in the series, but in Cartoon Network: Punch Time Explosion, it is Fred Tatasciore.
- Monkey might be an Honorary member of the Justice Friends, as he has connections with the group of heroes and all of them attended his birthday barbeque in the episode Barbequor and was called alongside them to fight Rasslor and Badaxtra.
- In the dial M for Monkey series, he is in love with Agent Honeydew, but in the later season episodes, such as "A Quackor Cartoon", he fell in love with Quackor, and in the later episode "Used Ink", one of the things that he asked for was a girl monkey implying that his relationship with Quackor might be over and he is looking for a new love allie.
- In the episode "Lab of Tomorrow", it was revealed that he could speak english.