Gumbald is a former gum person-turned candy person 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 had to reside 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 also a major antagonist in 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.