Ogdoad is a demon summoned by Peppermint Butler that possesses the body of Cinnamon Bun in "The Suitor." He apparently holds the key to the level eight Shadow Realm. Later on, Braco wants to be a love magnet so that Princess Bubblegum will love him, so he and Peppermint Butler ask Ogdoad to make Braco a love magnet. Ogdoad complies after warning that Braco's request will come at a price and then transforms Braco into an ugly creature with a third leg and swollen left arm. Peppermint Butler seems to find this attractive, meaning he at least fulfilled the arrangement.
Ogdoad is only seen when possessing Cinnamon Bun's body. While possessing his body, he has red and black eyes as well as very sharp teeth and a bat-like nose. It is currently unknown what his appearance is when not possessing someone.
- He has some sort of relationship with Peppermint Butler, for he knows what his name is when he was summoned. This is likely due to Peppermint Butler's connections to otherworldly creatures.
- Ogdoad is a word originating in Ancient Greek meaning "eight," or "eighth." The word was used in Gnosticism to refer to the eighth celestial sphere, above the seven planetary spheres.
- Peppermint Butler also refers to Ogdoad the character as "master of level eight shadow world."
- He bears a slight similarity to Eddie The Head, the mascot of the heavy metal band Iron Maiden (in the face at least).
- In Egyptian mythology, the Ogdoad (Greek "οκτάδα" the number eight) were eight deities worshiped in Hermopolis during what is called the Old Kingdom.