The Council

The Council is the main antagonistic force of Detentionaire. The mysterious Council consists of five members and has been first seen in "The Dance Part 2" as shadowy figures.

His Eminence
A semi-humanoid creature known only as "His Eminence" was accidentally freed from a state of suspended animation from inside of the pyramid by Alexander Nigma and, after leaving Alexander to die trapped inside the Pyramid, marked four of his best students with special Marks that would pass down to generations. He founded a cult around himself in plans of reopening the Pyramid at all costs, manipulating people in order to get what he wants and hiding some bits of truth to appeal to the current Council members.
 * Main Article: The Leader

Cassandra McAdams
Cassadra McAdams is the de-facto leader and figurehead of the Council. In addition to being the mother of Kimmie McAdams, she is also the CEO of the corporate conglomerate of Mann, Wurst and Finnwich as well as the maternal granddaughter of one of its founders, Elizabeth Mann.
 * Main Article: Cassandra McAdams

While the Serpent acts as the muscle and Fateous Mann - as the brains of the Council, Cassandra plays a role of a woman with money: she funds all of the Council's operations, including those directed towards world domination, and expects to see a profit from her plans.

Fateous Mann
Fateous Mann first appeared in "Escape from Fort Nigma", where the other members of the Council picked him up from the airport. He appears to be the group's resident hardware specialist, attempting to recreate The key stolen by The Red Tatzelwurm and later on attempts to implant a chip in his head to extract the Key's location.

The Serpent
Main article: The Serpent

Li Ping, reffered to as "the Serpent", first appeared in "The Dance Part 2" as a shadowed figure that grabbed Vice Principal Victoria's arm to take her to the Coral Grove. He was properly introduced at the pyramid chamber as he fought Blue Tatzelwurms off to protect the Council members. He first confronted Lee Ping when he stole the key from Lee's bedroom, after which the two of them numerously faced each other off, beginning the run of mutual rivalry.

The Serpent runs a downtown casino called The Hydra. Acting as the bodyguard of the Council, the Serpent often does the 'dirty work' for them, since he appears to be the most physically trained member. He is the one responsible for spying on the Ping family, notably Lee, although that interest in them is mostly personal. In season 4 the Serpent becomes a much more prominent antagonist, with his actions actively affecting the plot and some of characters' development.

Kerrigan
Kerrigan first appeared in "All That Taz". She seems to be the group's software expert. She has a strong hatred for Fateous Mann and regularly doubts that his plans will ever succeed. She was the one who told Cassandra that The Red Tatzelwurm had taken the second key based on information from Veronica Victoria's files.

Trivia

 * Judging by the way Mrs. Ping reacted to Lee's sketches of the Council members, she might know at least the basics about the Council and their plans.
 * Finnwich actively opposes the Council.
 * Three of five members of the Council (ss. Cassandra McAdams, Fateous Mann and Li Ping) are the descendants of the original MWF's founders.
 * The base for the Council's meetings is located in Mrs. McAdams' mansion in the secret hideout.