Gumball is a blue cat. On his oversized head, he has six whiskers, but only five are visible because his head is always at an angle. He usually wears gray trousers coupled with a tan sweater which is bordered with brown on the cuffs and collar (Which is shockingly revealed in The Date to have been found by his dad in a sewage outlet). Like his mother and father, Gumball doesn't wear shoes, and is the only member of the Wattersons (including Darwin) without visible eyelashes.
Gumball is very portrayed as a fun-loving, imaginative, optimistic, and a very mischievous cat. When his mishaps get himself into a mess, he usually attempts to put them right with somewhat dimwitted ideas, which usually get him into even more trouble than before. No matter how his schemes turn out, his optimism stops him from learning his lesson. He usually plans his mishaps with Darwin. Like Darwin, Gumball does not appear to acknowledge that he is being tricked, which may mean that he is too optimistic and to notice most negative things around him. Gumball seems to never learn his lesson.
He has a big ego and it is where he is most sensitive. He is usually positive on all matters concerning him. Surprisingly, he seems really stupid and smart at the same time. For instance, he acts really dumb and goes to great illogical lengths to find something. However, he has proven, time and time again, he makes this up with cleverness. This is shown with Darwin and him making well put videos for a 5 minute time frame within short notice. He has a better command of the English language than most, using words like "adjectives" rather than simply saying "words" when explaining to Darwin why in his opinion Great and Good are basically the same thing, and also using the word "trivial", despite not knowing words like "responsible" (though he knew "reprehensible"). It's possible that he uses above average grammar (for a seventh grader) for laughs. Gumball and Darwin's debate was rather well cut, implying Darwin understood as well, increasing his intelligence randomly.
Gumball may be smart, but not wise. He is a decent cook, making a very good sandwich for Darwin, as mentioned in The Secret, and is shown making some good (albeit spicy) meal for him in the same episode. However, in The Responsible, Gumball makes disgusting food for Anais, which included a rotten fish between bread slices and an old shoe. This may have been because they were both underestimating her though.
Gumball and Darwin are best friends and have a very close brotherly relationship. The two boys have a big imagination and like to get into mischief. They get along very well, although they argue at times. However, Gumball can be a bad influence on Darwin. Gumball sometimes turns his nose up at Darwin's ideas and they both go for a more childish or foolish approach. Darwin was once Gumball's pet, who sprouted legs for some reason, learned to talk and became able to digest food other than fish flakes.
Gumball usually relies on Anais with his problems. She likes to inform Gumball that she is right and he is wrong. Although Gumball will never admit it, he actually loves and admires his sister and knows that she is right about things most of the time.
Gumball loves his mother very much, though he does believe she is terrifying. He does not like to face the consequences of his actions and tell her if he does something wrong, because of Nicole's fiery temper.
Gumball loves his father very much, and inherits his silliness from him. However, Richard can be tough on Gumball when the situation demands it and he's also been known to make fun of him sometimes and use their foolishness to his advantage. As seen on an Elmore Stream video, Gumball likes to poke Richard's 'weird bit on his belly when he is unaware of it. Richard reacts strongly to this, making the same "dah!" noise after every poke.
Penny is Gumball's love interest. Gumball has a gigantic crush on her, and Penny has one on him, too. He often blurts that he loves/likes her and gets away with it either by keeping it as a secret, hiding it, twisting it, or hoping she ignores it. Despite it being somewhat obvious that Penny likes him back, he is always nervous when he has to ask her out on a date or even talk to her because he is afraid she might reject him. When they are about to kiss, the moment is usually interrupted. She has seen him naked in The Dress and in The Club.
Gumball always idolizes him to earn his favor. Ironically, Mr. Robinson despises Gumball for irritating him all the time. Although, in The Debt, Mr. Robinson does thank Gumball for saving his life, but then yells at him for ruining his great performance.
Gumball and Tobias have a history of rivalry behind them, although their relationship is somewhat unclear. In The Pressure, Tobias and Gumball form a no-girls pact and Gumball doesn't keep up with it very well. Also, in The Third, Tobias becomes Gumball and Darwin's friend for twenty dollars, but he ends up ignoring Gumball and befriending Darwin. It is clear that Tobias did this to upset Gumball.
Although the two never interact very much, their general relationship is always somewhat strained. Gumball has even said to Darwin that he never really did like Alan. Gumball has a tendency to forget his name, despite constantly being reminded. He usually calls him names like "Adam", "Adrian", "Arthur", "Alfred", "Augustus", "Albert", "Andrew", etc. He also seems to not acknowledge the fact that Alan is armless, being a balloon, thus ruining any activities that require hands (such as raising hands to prove innocence in The Mystery or playing games in The Third.
Gumball and Miss Simian strongly dislike each other. Miss Simian despises Gumball due to his mischievousness. Gumball despises her because she often gives him detention and gives out too many quizzes. Miss Simian usually gives Gumball detention if she catches him and Darwin planning something.
Gumball and Banana Joe have gotten along well in some episodes (The Pressure, The End, and a few others). However, in one episode, Banana Joe actually teases Gumball to tears, humiliating him in front of his classmates.
Gumball reluctantly lets Carrie use his body in The Ghost because of how Darwin said she was their friend. Carrie quickly took advantage of this, and did not respond well when Gumball forcefully told her to stop. Gumball later convinced her to stop, and it is implied that they got along fine after that. It is also interesting to note that in The GI, the final time the kids laugh at Gumball (before Penny stands up for him), Carrie does not appear to laugh.
Bobert, being a robot, has trouble making friends because of his lack of emotions. This doesn't stop Gumball and Darwin from trying to befriend him, though. First in The Third and again in The Robot, both times ended in pain for Gumball.
- "WHAT THE WHAT?!" -Catchphrase
- "I think cheese is better than cake, because you can have cheesecake, but you can't have cake-cheese!"
- [getting up a large hill using a tricycle borrowed from a little girl] "GOSH DARN IT!" [Gumball's Echo]
- "79% of stair accidents happen on the stairs."
- "Aww, nobody cares about the summer of '83!"
- [cheering up Darwin] "It's better to have loved, and watched that love burn before your very eyes, than to have never loved at all."
- "Save yourself! There's no time for me!"
- [Mr. Robinson is slowly parking behind a car while Gumball believes that he is being run over] "I just saw my life flash before my eyes! And it's boring!"
- "Welcome home, Mr. Robinson! I booby-trapped your front door!"
- [after reading a letter that states Gaylord Robinson will be assassinated at the talent show] "This is terrible! No, wait, this is what I've been waiting for!"
- [yelling at a squirrel] "There is no happy place!" [Gumball's Echo]
- "Hey Penny, I love you. Your painting! I love your painting!"
- "I love you! ...Ugh! What did I say that for?!"
- [reading Penny's note] "Will you be the jelly in my peanut butter sandwich?"
- "Do you know what I do when I feel like a loser? I look at this." [holds up a photo of a comical gopher holding up a large barbell]'
- "Stop throwing stuff at me!!! I'm innocent!"
- "I am a predator, hear me roar! [meows]
- "I'm bringing you back to life!"
- Darwin: "Okay, the answer is...[phone runs out of time]
Gumball: "NOOOOOOOOOOOOOOOOOO!!!!! NO! NO! NOOOOOOOOO!!!!!!!!!
- "Hey how its going?"
- [almost gets hit by a bucket full of solid concrete) "What the WHAT?!" (Awwww so close to a live swear...)
- "Check THIS out."
- Logan Grove (US/UK)
- Arthur Dubois (France)
- Junko Takeuchi (Japan)
- Federico Bebi (voice) and Leonardo Caneva (sing) (Italy)
- José Antonio Toledano (Mexico/Latin America)
- Rebekka Weissfeld (Danish)
- In The Dress, Gumball's fake name is GumBallOopsEggWobbleUnderpants.
- Gumball is terrible at catching things.
- Gumball hates watching the shopping channel, as shown in The Laziest.
- Gumball is shown to be a horrible liar on numerous occasions.
- Although Gumball has six whiskers, only five of them are visible most of the time.
- Gumball's name is a reference to the candy "Gumball".
- Gumball is a child character voiced by an voice actor of his age group rather than an adult.
- In The Picnic, he is shown to have claws, though he has never used them.
- He's allergic to make-up, unlike Darwin.
- He has very wide hips, which is unusual because this feature is more common on female characters in animation.
- Gumball placed 4th in the Dumb Race.
- Gumball's middle name is Christopher, though Richard confuses it for Tristopher.
- Gumball has arachnophobia, a strong dislike or fear or spiders, as shown in The Date.
- Gumball seems to be unskillful at many things (this includes roaring, swimming, and bravery).