He's a former gum person-turned punch bowl who was created by Princess Bubblegum to be her and Neddy's "Uncle." Princess Bubblegum first mentions him in "Susan Strong," claiming that he had cut down an entire field of taffy trees in a single night for some unknown reason. Finn and Jake were supposed to pull out all the tree stumps that he left behind, but only pulled out one before encountering a metallic hatch that led them to Susan Strong. Additionally, in the episode "Hot Diggity Doom," it is revealed that Gumbald built the log cabin that Princess Bubblegum and Peppermint Butler took refuge in after the King of Ooo took leadership of the Candy Kingdom. Gumbald was first introduced as the Punch Bowl in "The Enchiridion!," partying with many other Candy People.
He later appears in "Holly Jolly Secrets Part II" as one of Finn and Jake's video-watching guests, wearing a sweater that covers his mouth. He appeared again in the episode "Bad Timing," where he was invited to the presentation of Princess Bubblegum's time machine. He also made cameos in "Jake the Brick," "Hoots," "Hot Diggity Doom," "The Dark Cloud," "High Strangeness," and "Skyhooks" As Gumbald, he is first physically seen in "The Thin Yellow Line" being thrown in prison by Princess Bubblegum. However, the episode does not reveal who he is and the events didn't actually happen. His first true present appearance is in "Three Buckets," where he collects Fern's remains and asks him if he'd like an Uncle.
He is not truly named until the episode "Bonnibel Bubblegum." (In "The Wild Hunt" he is simply called Uncle G.) It is shown that he is possibly as skilled a scientist as Princess Bubblegum in "The Wild Hunt," as he created the Grumbo, a large, hot fudge-shooting Banana Sloth that had been attacking the Banana Guards. He is one of the two main antagonists of the series finale, "Come Along With Me." After experiences with his niece in the Dream Realm, he makes amends with her before being turned back into Punch Bowl by Lolly. Once he is revealed to be lying, Lolly then takes his place as ruler of Gumbaldia.
Not much is known about Gumbald in the beginning of the series, as Bubblegum scarcely talks about him. In "Susan Strong," it is mentioned that he cut down an entire field of taffy trees in a single night for the Candy Kingdom.
He is mentioned again in "Hot Diggity Doom" when Princess Bubblegum tells Peppermint Butler that Gumbald had built the cabin they were repairing during Bubblegum's exile.
In the "Thin Yellow Line," Gumbald is seen during the Banana Guard's story about the Princess, detailing how dangerous and mysterious the guards see her. In the story, Gumbald is seen thrown in jail, cowering. It is not revealed he is Gumbald until later on.
In "Three Buckets," Gumbald makes his first appearance in the present, as well as his first speaking role. He wears a cape with a large "G" logo on it. After Finn accidentally shreds Fern with his prosthetic arm, Gumbald is seen putting Fern's remains in a bucket, and he asks the pile of grass if he needed an Uncle. He is not named in this episode, but his first line hints at his true identity.
In "Bonnibel Bubblegum," it is revealed that he was created by a lonely Bonnibel Bubblegum. She wanted to have more family than just Neddy. Due to this, she created Uncle Gumbald, along with Aunt Lolly and Cousin Chicle. They lived peacefully as Gumbald and the rest of the family built a candy town and planted taffy trees. However, Gumbald cut down the taffy trees to build a log cabin. He revealed to his niece that he had plans to build a candy city. Bonnie, however, did not like that idea so she used a butterscotch bomb to make Lake Butterscotch where Gumbald intended to build the city. This infuriated Gumbald but, he had a backup plan. He sent Bonnibel away after creating her a boyfriend, Mr. Cream Puff. While she was away, Gumbald along with Bonnibel's other intelligent relative-creations, Lolly, and Chicle were discussing a plan to overthrow her and build a candy city. He formulated a "happy juice" that would make Bubblegum more docile and simple-minded like Mr. Cream Puff. Gumbald tricked Lolly and Chicle into eating happy juice cupcakes, turning them into Manfried and Crunchy, forgetting their previous selves. Bonnibel caught this. Gumbald voiced that Bonnie tried to keep him in line but stated he was her equal as she denounced him as evil. He tried to make Bonnie have the juice while threatening her brother Neddy but with the help of a peashooter, she shot the beaker with the happy juice while Gumbald was holding it. The happy-juice splashed onto Gumbald's face and turned him into the Punch Bowl and forgetting his previous self. In the end, Bubblegum becomes aware he is back since she recognized the cup BMO had got from a scientist.
In "Seventeen," it is revealed the Punch Bowl was reverted into his previous-self, Gumbald due to the events of "Skyhooks II," in which Lumpy Space Princess' anti-elemental lumps reverted everything into its "true shape." Gumbald and his family disguised themselves as a horse for a warrior revealed to be Fern. Gumbald stops Fern from killing Finn and revealed himself along with his family to Bubblegum who was shocked to see him. He revealed how they changed back to normal and tried to turn Bubblegum into a candy person for keeping them trapped for centuries but Marceline interfered. Scared by her, he decided to retreat along with his allies though promised to be back.
In "Gumbaldia," he is shown to have achieved his goal of building a candy city which named Gumbaldia and is preparing for war against the Candy Kingdom even making jokes about his niece's impending demise. However, he was surprised Finn and Jake saved him even though it would save them the trouble of war. Gumbald then acted cordially to them and called off the attack, he even protected Lolly from being spilled on. However, his actions were proven to be a part of the plot as it was revealed he and Lolly conspired to change Bonnibel into a candy person to lower her kingdom's defense. When this failed, he gathered most of Finn and Jake's enemies to help in his attack.
In the series finale "Come Along With Me" he and Princess Bubblegum are preparing for war against each other. Finn not liking the idea, got the two of them talk before the war began. Jake then unleashed nightmare juice, placing he, Finn, Gumbald, PB, and Fern into a nightmare together.
Inside the dream realm, PB and Gumbald continue to be hostile towards each other and despite Finn's protests, PB decides to pursue Gumbald. PB and Gumbald recreate a nightmare version of the moment that PB defeated Gumbald by dousing him with his own dum-dum juice, only this time with the roles reversed. PB is doused and is transformed into a smaller, less intelligent version of herself, while Gumbald was placed in the life of his niece, being very paranoid about the safety of the Candy Kingdom. Gumbald and PB are later brought to tears after both witness the Candy Kingdom turn into a pile of goo in the dream.
After the four of them wake up from their dream, PB apologizes to Gumbald for not respecting his vision for the Candy Kingdom. Gumbald fake-accepts her apology and agrees to end the conflict, intending to betray her, but is tripped by Aunt Lolly and once again doused in his own dum-dum solution, turning back into Punch Bowl. At the end of the episode, Punch Bowl is seen at the Candy Tavern, enjoying a toast with Crunchy, Starchy, and Dirt Beer Guy.
As Punch Bowl, he appears as a large glass bowl of fruit punch with large white eye with purple pupils.
As Gumbald he appears as humanoid gum person with a piece of hair on the top of his head. He also has a mustache and a beard on the bottom of his face. He is seen wearing an article of royal clothing but also appears wearing a tan tunic and purple cape.
As Punch Bowl, not much was known about him as most of his appearances were brief cameos, but he seemed to be a simple-minded candy person with low intelligence, who enjoyed having fun and parties.
In his true form as Gumbald, he is shown to be very intelligent, on the same level as his "niece." When he was first created, Gumbald was very kindhearted and even thanking Bonnibel for giving a "Greatest Uncle" mug. However, he eventually got tired of following Bonnie and made plans to create his own kingdom. He got angry at Bonnibel's attempts to sabotage them, and slowly made plans to overthrow her; to that end, he created a boyfriend to distract her and turned her other created relatives Lolly and Chicle against her.
After turning back, he has made plans to exact revenge on Bonnibel as well as those she has befriended as he created a new body for Fern and had him attack Finn though prevented him from killing Finn. When he revealed himself, he tried to turn Bonnibel into a candy person and would have succeeded if Marceline had not interfered. He also shows a sense of survival, as he didn't try to attack Bonnibel again since in his words "the vampire girl is legitimately scary," which caused him to retreat.
Gumbald is very self-centered and narcissistic, as proven by his design for the family crest, as well as the paintings and decorations inside the Gumbaldia castle. He thought of himself as Bonnibel's equal before turning into a candy person. He also showed no remorse in using the Dum Dum Juice on his partners, who had been nothing but useful to him though he did protect Lolly from being changed after Finn and Jake nearly sprayed Dum Dum Juice on her.
- "The Enchiridion!" (as Punch Bowl, unofficial debut)
- "Holly Jolly Secrets Part II" (as Punch Bowl)
- "Bad Timing" (as Punch Bowl)
- "Jake the Brick" (as Punch Bowl)
- "Hoots" (as Punch Bowl, dream)
- "Hot Diggity Doom" (as Punch Bowl)
- "The Dark Cloud" (as Punch Bowl)
- "The Thin Yellow Line" (cameo, flashback)
- "High Strangeness" (as Punch Bowl, cameo)
- "Hero Heart" (as Punch Bowl)
- "Skyhooks II" (as Punch Bowl)
- "Three Buckets" (physical debut; not named yet)
- "The Wild Hunt" (not named)
- "Together Again" (snow golem/hallucination)
- Despite Uncle Gumbald literally having the word "bald" in his name, he is not entirely bald.
- In his candified form, he appears to be much more goofy than other Candy People.
- Him and Martin Mertens are both parental figures shown in a bad light within the show. They're both also parental figures to the main characters.