GOLB

GOLB is a malevolent entity related to chaos who inhabits an unknown dimension and serves as the final antagonist of Adventure Time.

He is first seen briefly at the end of "Puhoy." After old Finn dies in the Pillow World and is being warped back to his own reality, he bounces off GOLB's tongue.

He is mentioned later in "You Forgot Your Floaties." While inside Magic Man's mind, Betty witnesses a memory of him and Grob Gob Glob Grod discussing GOLB at an unknown date in the past. It is revealed that GOLB attacked Mars at some point and "took" Magic Man's wife, Margles. Grob Gob Glob Grod believes that GOLB will return and Magic Man agrees, using the threat of GOLB as a pretext for building a security system on Mars that takes the shape of Margles. Later, Magic Man changes his mind, claiming that Grob Gob Glob Grod is wrong and GOLB is "probably not coming back."

The Lich calls himself the "last scholar of GOLB" in "Whispers."

In "Temple of Mars," Betty speaks to Magic Man (now known as King Man) about her plan to both save Simonfrom the ice crown and to get back Margles from GOLB.

In "Come Along With Me," Betty, Maja, and Normal Man summon GOLB to Ooo, and he wreaks havoc by combining the candy people's mass to create hostile wraiths. Upon seeing him, Ice King has a flashback to an indeterminate date in the past when he researched GOLB as Simon. In the flashback, Simon describes GOLB as a "mysterious entity who embodies chaos," and states that "his presence is felt in every crevice where chaos lurks." When GOLB arrives, he swallows Finn, Betty, and Simon. Simon and Finn manage to escape before he digests them, but Betty stays behind to try to use the Ice Crown to wish GOLB away from their world. Her first wish to destroy GOLB fails because GOLB's power supersedes that of the Crown, but her subsequent wish for "the power to keep Simon safe" succeeds and allows her to merge with GOLB into a single entity. The newly-created Betty-GOLB exits Ooo, leaving the Ice Crown behind.

Trivia

 * GOLB will appear in the final episode of the Chris the Lion Adventures.