Mirror World Nobita is the main antagonist in the episode The Opposite World Mirror. He is the opposite of Nobita's personality, being nasty and wicked, and thus effectively "the worst person" of all. The character makes his home in the Mirror World. Nobita Nobi encounters him after he tries to make his getaway from Takeshi Gouda and Suneo Honekawa bullying him.
The Bully-Noby mimics the true Nobita for appearance and body frame, but he is much worse than his real counterpart's Takeshi Gouda, with a tyrannical, sadistic bent. Because of this, Nobita has to seal him away. Shizuka eventually seals away the monster with the Opposite World Mirror.