The Deranged Ringmaster (also known as Evil Ringmaster, Outraged Zidler or Evil Circus Master) is the boss of the Nightmare Circus. In order to fight him, the host of the party needs a Golden Stage Ticket. If the host has ticket, then upon defeating the Ringmaster, he becomes the Deranged Ringmaster.
The Deranged Ringmaster is a skeletal version of himself with a blue-flame aura. The toy horse he rides as the Ringmaster turns purple following his transformation. The background will also change into that of a burning circus with fiery wreckage, showing that the extent of the damage caused by the fight between him and the Grand Chase.
The attacks of the Deranged Ringmaster are similar to the Ringmaster.
The Deranged Ringmaster can shoot out quick-moving rockets that can absorb HP with the horse and can also perform a Jump attack, sometimes with no warning, and can create an area of poisonous purple gas that damages players and gives them the Haste status. He can also attack with his baton.
Sometimes the Deranged Ringmaster will toss three bombs. If the bombs do not hit the player, Jugglers will be summoned to assist him during the fight.
During the fight, the lights will go out at set intervals, restricting a player's viewing area to a small area of light surrounding their character. To turn the lights back on, players must hit a switch situated at the centre of the map on the lowest platform. While the arena is dark, the Deranged Ringmaster will take significantly less damage from attacks.
- The Ringmaster and Deranged Ringmaster's left foot seems to have been injured before for an unknown reason.
- A glitch exists that causes the switch to permanently light up the arena. This can "possibly" be done by attacking the switch with very fast multi-hit attacks.
- Voice Actor : Si Yeongjun.