Many characters of Fanboy and Chum Chum have held antagonistic roles in various episodes, even though they are normally portrayed as heroes. This is a list of antagonistic traits shown by otherwise good characters. This list doesn't not include Boog, Janitor Poopatine, Global Warmer or any other villains who are already evil most of the time.
Keep in mind, although Fanboy is a Fan of Everything, he often explodes with rage when things don't go as planned, and is often annoyed.
- In "Pick a Nose", he angered Chum Chum to give him his nose back.
- In "Digital Pet Cemetery", he got so annoyed by Scampers' beeping that he overfed him. He also constantly crashed him and kept bringing him to life.
- In "Fanboy Stinks", he refused to bathe and caused everyone to pass out.
- In "Berry Sick", he wanted to keep Berry from returning to the Frosty Mart.
- In "The Great Bicycle Mystery", he constantly accused someone of breaking Lenny's bike. NOTE: This is the first episode to portray Fanboy as the villain.
- In "Speed Eraser", he accidently erases Kyle's body and erased his wand as well when it's really important.
- In "Hex Games", he foolishly zapped Kyle instead of the Gooper.
- In "Buddy Up", he turned into a caveman and broke Kyle's wand.
- In "Secret Club", he and Chum Chum refused to listen to Kyle's orders and ate everything in his parlor.
Chum Chum may be sweet and cute and all, but he has frequently acted mean at times.
- In "Pick a Nose", he refused to give Fanboy back his nose, although he angrily asked for his earlier.
- In "Dollar Day", he didn't believe what Fanboy said about losing their only dollar, but was only faking it.
- In "Digital Pet Cemetery", he constantly kept crashing on Scampers.
- In "Berry Sick", he repeatedly used Fanboy to hit the Frosty Freezy Freeze machine and threatened to eat Berry.
- In "Boog Zapper", he ruined Oz's new Touch Tone Touch Screen Touchinator 2000 by shooting it with an arrow and menacingly told Oz to leave.
Kyle has a considerable but not really evil antagonistic side, due to being constantly annoyed by Fanboy and Chum Chum. He frequently takes advantage of the situation to stop them from tormenting him, which works, having him to tone his negative traits down and work with him as the series goes.
- In "Wizboy", he sneakily shoos Chuggy out of his seat and takes it. He also went crazy and threatened to destroy Fanboy in the wizard-off.
- In "Precious Pig", he mocked Fanboy by blowing a raspberry at him.
- In "Separation Anxiety", he laughed at F&C's punishment, and constantly stopped them from getting together. NOTE: This is the first episode to potray Kyle as the villain.
- In "The Book Report of the Dead", he mocked Fanboy for not finishing his book report in the hall.
- In "Lord of the Rings", he drove himself crazy trying to learn Fanboy's ring trick, such as taking the rings from him.
- In "Tooth or Scare", he sets up booby traps due to F&C running amok his dining room, and scolds them for doing that, thinking about serving them to the serpent in the mith.
- In "There Will Be Shrieks", he mocks F&C about their "haunted house" idea.
- In "The Winners", he threatened to char F&C with the "Fires of Ragnar" so he can steal their winning cup.
- In "Speed Eraser", he gave Fanboy a magic eraser and hoped he'll get in trouble. He also cast a spell on the eraser which sticks it to him, leaving him to erase anything he reaches out to. NOTE: This is Kyle's meanest role of all time.
- In "Buddy Up", he forced to feed F&C to the dinosaur to get away.
Yo is always sweet and gentle, but always gets angry due to not having to play with Chum Chum.
- In "Trading Day", she decided not to trade Chum Chum back due to Fanboy not bringing back her Mechatech.
- In "Prank Master", she constantly pranked Fanboy.
Hank is always known to be mean a lot, and even shows this to the class by doing something bad.
- In "Wizboy", he steals Kyle's wand, thinking it's a stick and wouldn't give it back until the year is over.
- In "Excuse Me", he forced the main 3 to work during Spring Break.
- In "Saving Private Chum Chum", he took everyone's toys away and constantly zapped them with his laser eyes, thinking they're Night Monsters. NOTE: This the the first episode to potray Hank as the villan.