King of Ooo

King of Ooo appeared in "Apple Wedding." He is a controversial figure in Ooo of debatable power, who travels in a blimp he calls his "zep" and apparently maintains a website, "kingofooo.com." He seems to hold a cult-like sway over some inhabitants of Ooo who consider him their proper ruler, though it is unclear if he actually is a king or just a con artist taking advantage of his "subjects."

Apparently, Princess Bubblegum does not accept his authority as a king, though Tree Trunks and Mr. Pig do apparently recognize him as "the One True King of Ooo," along with a number of their relatives. He is shown making metaphorical declarations to Mr. Pig's relatives, such as interpreting their imagined "thought-forms" and granting "one year good luck" to them based on their "visions."

Princess Bubblegum also personally dislikes him, even going so far as to break into his blimp to search it and prove him a fraud and con man. There she finds an expired certificate stating his right as a priest for Tree Trunks's wedding. She tries using this as a reason to arrest him, but is proven wrong when the King Of Ooo tells her she probably found it in the old section of his blimp, and pulls out a new certificate out of his pocket. Princess Bubblegum nevertheless has him arrested and thrown in the Candy Dungeon, along with the other attendants of the wedding when they protest her poor behavior and refuse to recognize her authority.

The King's dubious authority includes a clause in the wedding vows that would make Tree Trunks and Mr. Pig his servants for a five-year period, but he does not get to complete the wedding before Princess Bubblegum literally crashes the party in his "zep." He later escapes the Candy Dungeon by eating the bars in fear of Bubblegum's wrath and tells Tree Trunks to "perform her own dang ceremony," which she and Mr. Pig take literally as a declaration from "the One True King of Ooo" to marry themselves.

Because the rulers of the various "kingdoms" in Ooo are princesses, it is probably more accurate to say that Princess Bubblegum (as well as all other regnant princesses) is the ruler of a principality (The Candy Principality) that in turn would be subject to the sovereign to a king of Ooo. Principalities (in the real world) can be sovereign, but more often than not the prince or princess of the realm is subject to the King. The fact that Princess Bubblegum does not recognize his authority likely means she does not recognize Ooo as being a unified Kingdom and views her principality as sovereign.

Appearance
The King of Ooo is a tall golden being with thick puffy golden brown hair and a mustache, along with a single mole on his face. He wears a broad-shouldered brown coat with gold trim and several gold rings, which has a lighter brown pair of pants and button-down shirt beneath it, along with a crown. He carries a scepter with a winking smiley face on it. According to the Adventure Time crew, he is made of earwax.

Trivia

 * The King of Ooo is also the namesake/mascot of the Tumblr blog for the Adventure Time crew, KingofOoo.Tumblr.com.
 * In the storyboard for "The Tower," the King of Ooo's crown appears as one of the objects Finn uses to build his tower.

Screenshots
Rey de Ooo