He is voiced by Davy Johnson
He always spanks them for his own pleasure and treats them like slaves, which leads them to become more subservient and filled with fear.
In the episode "The Silent King" Finn and Jake defeat Xergiok, driving him out of his kingdom. Later, he returns to take back his kingdom, but is defeated again when Finn and Jake defeat his Earclops army with loud sounds and one falls on him. He escapes and fires fireballs at Finn and Jake, but one of his own fireballs hits him, knocking him out. Finn picked up his magic wand and ate it.
He also appears in "All the Little People" as a toy version of himself along with many other characters from the show. Throughout the episode he is seen being spanked by Turtle Princess.
In "Bird Man" Xergiok was revealed to be not killed; after his defeat, he fled, had both of his eyes removed by a wizard (who didn't take them, but instead left them with Xergiok in his beard) and later lived a life alongside birds, earning him the nickname of the Bird-man. However, after he restored his vision he started acting like his old self again which cost him his bird friends. After that he removed his eyes and gave them to Finn and Jake who put them back in his beard, He then went into a lake where he got a mermaid girlfriend.
- According to "The Adventure Time Encyclopædia," he is one of Hunson Abadeer's poker buddies "who still owes him money from a hand of Texas Hold'em."
- His voice is similar to another character's voice from the 1985 series Thundercats.
- In "The Great Bird Man," it is revealed that he donated his kidneys to a hospital.