The Bufo are introduced in "Wizard." They are a group of tadpoles that live inside the vocal sac of a toad (who is possibly their father).
They bestow Finn and Jake with wizard cloaks. They teach Finn every level of wizardry until he became a master, and only then inform him he has to make a vow to become an Ultimate Wizard. Finn accepted without even knowing what vow he had to make, though the Bufo tried to warn him saying that he wasn't familiar with the terms of the vow.
Finn, upon accepting the pledge, was led to a room where he would protect the wizard training facility from a meteor with the Old Wizards for the remainder of his life, using the powers to keep the meteor away. The Bufo admit to tricking people, but the fact that he did make some effort to warn Finn of the terms shows that the Bufo try to be at least a bit fair. At the end of the episode, the Bufo begin to renounce all magic, but Finn interrupts telling them it is unnecessary to quit his job and that he only had to stop taking credit for ideas that aren't theirs. They then took credit for that idea out of Finn's earshot. One of the tadpole's names (obviously known as Leonard) was revealed because he wasn't talking in unison with the other Bufo. The Bufo also appear as a contestant in "Wizard Battle."
The toad host reappears in "Reign of Gunters" in a secret wizard's club Ice King accidentally discovers. He and his fellow wizards attempt to kill Ice King in an offscreen battle that Ice King escapes from. The toad mentions undergoing various dangerous initiations and rituals to achieve a higher level of power, which includes taking the advice to "beef in the eye of Glob and stuff" to the amazement of fellow members Laser Wizard and Forest Wizard.
The toad reappears again with the secret society in "Wizards Only, Fools," where they attempt to sacrifice Abracadaniel before being interrupted and teleport to a mysterious dimension to avoid trouble with the Wizard Police. The toad is directly referred to as "Bufo" this time, implying that is its name as well. It appears again with the society in "Betty" when they summon Bella Noche.
In the events of "Wizard City", they drink the ichor of Coconteppi and seemingly die. Later it's revealed that only the frog body died, and that the tadpoles survived and wantd to be placed into Cadebra's body. When that is thrwarted, Choose Goose arrives (also being thought dead from drinking the ichor) and imbibes the Bufo, going dark.
The Bufo themselves are a group of nine teal tadpoles with purple wizard hats on their heads.
The toad the Bufo live inside of is green-skinned with red eyes, yellow sclera, and dark blue spots on its cheeks. He wears a purple robe with a yellow star on its center and a pair of purple wizard hats on its head. He places the hats on top of his vocal sack when he expands it and the Bufo appear, to signify the Bufo have "taken control".
- "Wizard Battle"
- "Reign of Gunters"
- "Wizards Only, Fools"
- "Hoots" (cameo)
- "The Comet" (comet projection)
- There are nine Bufo for most of the episode, but ten of them are shown near the end.
- Like the Witch from "The Witch's Garden," the Bufo use the "Razzamafoo" spell to bring Finn and Jake closer and/or swap places.
- The Bufo host may be named Bartholomew.
- The host of the Bufo may be a male Darwin frog because, after the tadpoles hatch, the males keep the tadpoles in their vocal sacs.
- The name Bufo is a Latin word for "toad," which is also the genus classification for toads. There are several toads of the genus Bufo which secrete psychedelic substances from their skin, including 5-MEO-DMT (5-methoxy-dimethyltryptamine), and bufotenin (5-HO-DMT). Both are similar to N, N-Dimethyltryptamine, which is referenced in the episode "The Real You."
- There is also a former constellation named "Bufo" which was created in 1754, outlining the shape of a toad in the stars.
- in Wizard City when he clicks his tongue and points with both index fingers ("finger guns") this is a tribute to Fonzie from Happy Days