- "Adventure is out there!"
- —Muntz's famous catchphrase
Charles F. Muntz is the main antagonist in Up.
Muntz is a famous explorer who was an adventurer that Carl and Ellie admired when they were kids. He is also an avid dog lover and inventor, being able to train them to do practically anything, and has invented devices that translate their thoughts into speech. He is the master of many dogs, including Dug (who is now Carl and Russell's pet, and Carl and Russell are now Dug's new masters), Alpha, Beta, and Gamma.
He departed for South America after scientists claimed that Muntz had faked his discovery of the skeleton of a 13-foot tall tropical bird, vowing to find a living specimen. Unfortunately, the countless years that Muntz spent there had corrupted him, making him extremely greedy, dangerous, and paranoid, believing that anyone who came to Paradise Falls was after the bird to steal his glory. Muntz is first seen in a film titled Spotlight on Adventure, when an 8-year old Carl is visiting the movie theater. It is explained that he had recently returned from a lost land called Paradise Falls, having completed a year-long survey. In the next scene, Muntz presents himself on a stage in front of his audience showing off his new-found treasure of a tropical-bird skeleton, whom he calls "The Monster of Paradise Falls". After a scientist rips Muntz's badge off his jacket, he speaks into a microphone to an oversized crowd promising to return to Paradise Falls to get the bird, protesting that he will not come back home until he does. Muntz tells Carl and Russell that during the 1930s and the many other years, he had lost so many of his dogs.
It is revealed that Muntz has become quite ruthless and evil in order to obtain the bird; he goes as far as to try killing Russell, among other things. After a chase, Muntz leaps out of Carl's house and grabs Kevin's tail feathers. But Muntz's foot gets tangled in the balloons which detach from Carl's house, which makes Muntz fall thousands of feet below to his death.
Dug's Special Mission
Muntz is mentioned by Alpha in the short as "Master".
Muntz was a determined, greedy, insane, angry, paranoid, ruthless, bitter, evil man.
Near the end of the movie while trying to retrieve Kevin, Muntz's leg gets caught in some balloon lines and ends up falling to his death after being knocked off his zeppelin, the Spirit of Adventure (along with Carl's old house).
- Muntz: "You know, Carl, these people who come here, they all tell pretty good stories. A surveyor making a map... a botanist cataloging plants... an old man taking his house to Paradise Falls... and that's the best one yet. I can't wait to hear how it ends."
- —Muntz to Carl
- Muntz: "Enough! I'm taking that bird back with me...alive...or dead!"
- —Muntz, his last words as he fights Carl, destroying his prized possessions
- His name comes from Charles Mintz, who tried to sue Walt Disney for their Oswald the Lucky Rabbit character (from where the Mickey Mouse character later spawned).
- Muntz is the third Pixar villain to fall to his apparent death preceeded by Emperor Zurg (who actually survived), and GO-4, but the eighth Disney Villain overall to do so (after the Wicked Queen, Ratigan, McLeach, Gaston, Frollo, Zurg, and GO-4.)
- Muntz is also the third Pixar villain to die at the end of the movie, the first two being Hopper and Buddy Pine.
- Muntz is the sixth Pixar villain to be physically fought.
- At the start of the film, Muntz was thought to have been a minor protagonist, but is revealed to actually be the antagonist.
- When talking to Carl, Muntz talks about being on Safari with Roosevelt. It is hard to tell if he means Theodore Roosevelt or one of Roosevelt's sons or his nephew, Franklin Delano Roosevelt, as Theodore Roosevelt passed away in 1919, when Charles was only 3 years old.
- The ultimate fate of Muntz was a work in progress for Pixar as they tried several versions to get him out of the way so the film could get back to Carl and his connection to Ellie. First they tried giving Muntz a chance to redeem himself to the point where it resorted to just him talking with Carl. Then they tried an ending that was reminiscent of Stanley Kubrick's version of The Shining where Muntz goes after Kevin in the labyrinth, where he's left to wander forever, but it felt more like Muntz's ending than Carl's ending. At that point, Pixar decided to place the climax on the Spirit of Adventure and one version had Muntz trapped in the house as it floats away, but it felt wrong due to the house being seen as Ellie. Another version had Muntz caught in a bunch a balloons and floating upwards, but it left an uncertainty as to whether he was dead. It was at this point that Pixar decided the best comeuppance for Muntz was for him to get caught in the balloons and fall with them. This is discussed on the DVD extra "The Many Endings of Muntz".
- An easter egg found in the Blu-ray version titled "The Egg" discusses an idea about Kevin's eggs restoring youth when consumed. The egg is what Muntz goes after in this version and it is not known if he still wants to clear his name. The idea was later abandoned.
- Although he dies at the end of the film, he is shown to be still alive in the Kinect Rush: A Disney/Pixar Adventure video game, along with that his dogs are still evil in the game. It could be that he might have survived the fall, and that he used some different dogs.
- Christopher Plummer, Muntz' voice actor, played Captain von Trapp from The Sound of Music and voiced the Grand Duke of Owls from Rock-a-Doodle and voiced the narrator in the Madeline franchise.
- Muntz has his own musical theme composed by Michael Giacchino that's the first piece of music heard in Up. It echoes through the film when Carl and Russell meet him 70 years after young Carl sees Muntz in the newsreel at the beginning. A twisted version plays when Carl realizes Muntz's intention of capturing Kevin and killing anyone who gets in his way. Finally, the theme plays against Ellie's theme during the climactic battle between Carl and Muntz.