Jester the Pester is a gremlin/jester-like monster and is one of the many monsters of the Underworld. He is the first monster to be summoned by Imperious. He serves as one of two main antagonists (alongside Imperious himself) of the episode "Long Ago".
Jester was called forth by Imperious to use Dark Magic and attack the city. He was also given a Dark Pen to use in the city. With his first attack on the city, he terrorized the citizens of Briarwood, all the while drawing fake mustaches on people's faces, until the Mystic Force Rangers showed up. The Rangers fought as best they could, but the monster was too fast for them, and after the Madison saves two people, he managed to get away. However, before he did so, he placed a strange marking on the ground with the pen he had been given which caught the Ranger's attention. When he returned, he was about to place another symbol on the Earth. But before he could, the Mystic Rangers came by and the Blue Ranger used her Water Power to blast Jester away and washed the marking off, she realized that he was planning on creating a giant Dark Seal on the city that will destroy the people of Briarwood. Jester explained the rest of his plans and attacks the Rangers, now highly annoyed, the Blue Ranger tried to battle the monster alone, but she was outmatched and after being hit hard, she demorphed.
Right before Jester could finish off Madison with his Right Arm Three Bladed Claw, a frog jumped on him, and (Jester hates frogs) distracted him. This allowed the other Rangers time to get into the fight, but Jester was still too powerful. While the other Rangers fought Jester, Madison kissed the frog that had saved her. That kiss broke the spell on the frog, and returned him to Daggeron. Once freed, Daggeron set out to take on Jester and the Hidiacs that had been summoned. The hero morphed into the Solaris Knight and took on the Undead Warriors with the Laser Lamp. The Hidiacs were defeated easily, Jester tried to escape through a wormhole in the ground, but the Solaris Knight used his Laser Lamp to force him out of the ground, Jester was finally destroyed by Jenji's Shinning Attack fired from the Laser Lamp by Daggeron.