Iacedrom and Ygbir are photorealistic-looking counterparts to Mordecai and Rigby. They both wear top hats and speak very formally. They are the leaders of the Dizzy Zombies and the supreme rulers of the Dizzy World, which exists in Pops Maellard's mind.
In the episode "Dizzy", Iacedrom and Ygbir met Pops Maellard when he came to the Dizzy World after getting Dizzy. After presenting themselves, they gave Maellard some ice cream, telling him that they outlaw speeches (which was the reason Pops came there, as he was going to have an speech at the Park), and that it was also illegal to not enjoy the ice cream, much to Pops' and the Dizzy Zombies' delight.
When Mordecai and Rigby, Iacedrom's and Ygbir's real life counterparts, went to the Dizzy World to rescue Pops, he refused to accompany them to the real word stating that he was okay. As Mordecai and Riby still begged him to return, Pops became angry and unknownwingly ended up giving an speech. Congratulated by Mordecai and Rigby, Pops became so happy that he told Iacedrom & Ygbir that he didn't need to remain more at the Dizzy World as he know had overcome his fears. Furious, Iacedrom and Ygbir told Pops that he indeed needed to leave the Dizzy World for giving an speech, but Mordecai and Rigby took Pops with them and proceeded to return to the real world. Although Ygbir was unable to follow them, Iacedrom flew in order to eat Pops, Mordecai and Rigby, but there eventually managed to escpae thanks to Skips' help.
In the episode "Pops' Favorite Planet", Iacedrom and Ygbir were later seen on hieroglyphs a the observatory.
In the series finale "A Regular Epic Final Battle", as a result of Pops' death in order to kill Anti-Pops in order to save the entire universe in the process, although they didn't appear or were mentioned, Iacedrom and Ygbir were consequently erased from existence along the Dizzy Zombies and the Dizzy World itself as the mind of the person who created them was no more.
- While Iacedrom is Mordecai spelled backwards, Ygbir is Ribgy spelled afterwards, not Rigby.
- In the Latin Spanish dub, Ygbir was named Ybgyr, just like an unrelated villain who appeared in the episode "Jinx".