|Relationship||Judy Neutron (one-sided), Elke Elkberg ("Carl Wheezer, Boy Genius")|
|Family|| Ebenezer Wheezer (dad)|
Martha Wheezer (mom)
|Friends||Jimmy Neutron, Goddard, Sheen Estevez, Libby Folfax, Cindy Vortex|
|Likes||Llamas, Judy Neutron, and food.|
|Dislikes||Germs, lima beans, scary stories, and Hugh Neutron|
Carlton Ulysses "Carl" Wheezer is Jimmy's neurotic, llama-loving, best friend. According to canon, he is 12 years old. He is known as nervous, timid and suffering from asthma and hypochondria. At times, he tries to overcome these personality traits in order to appear "cooler" around Jimmy and mutual friend, Sheen, even though he has a sensitive Scapula and spine. He has many talents, the most recognizable is his extraordinary singing ability. He is voiced by Rob Paulsen.Carl also appears to be in love with Jimmy's mother, Judy Neutron, accidentally saying that she is beautiful around Jimmy and Sheen, carrying around a picture of Jimmy's parents with his head pasted over Jimmy's father's face. In many times in the episode "Love Potion 976/J" Carl really dislikes Jimmy's father, Hugh Neutron, whenever he is around. Though, in "Carl Wheezer, Boy Genius", his love interest was Elke Elkberg, his Swedish pen-pal who was voiced by Grey DeLisle.
Carl likes to eat, and this caused him to be overweight. When his parents expanded their cable line-up, Carl found himself focusing on a channel devoted to llamas and a show about a superhero called Llama Boy the Super Hero. He has adored llamas ever since, going so far as to join a fan club, The Llama Love Society (Which he likely created as he is shown to be the first member). He once turned into a llama. He is allergic to almost everything.
In the episode, "Normal Boy," it is revealed that Carl is the inventor of the "Hot Dog Holder Deluxe", also known as "The Versa-Bun (which is a normal hot dog bun, that he didn't really invent)." It is revealed in "The Incredible Shrinking Town" that he took ventriloquist lessons, and that he can virtually imitate and sound just like everyone. It is also a hinted that he has some sort of dislike for Sheen. Carl enjoys playing a video game called Llamapalooza.
It was stated by himself that he as always wanted to touch a Llama in the Jimmy Neutron: Boy Genius Movie
Carl has peach skin and many freckles. He has a pair of small black eyes and red hair. He often wears an orange-and-red-striped shirt, a pair of green pants (shown with suspenders in the movie), a pair of brown loafers, and glasses.
Carl has appeared in all of the episodes of The Adventures of Jimmy Neutron: Boy Genius along with Jimmy and Sheen. His first appearance was in Runaway Rocketboy!. His last appearance was in the series finale "Jimmy Timmy Power-Hour 3: The Jerkinators". He also appeared later in the spin-off series, Planet Sheen, during Sheen's flashback of him and Carl in the episode Is This Cute? when comparing similarities between him and Doppy. He also appeared in the ride Jimmy Neutron's Nicktoon Blast. He and Doppy has the same voice and resemblance
- Carl Wheezer is similar to Milhouse van Houten fron The Simpsons.