Fanboy and Chum Chum
Voiced by: David Hornsby (Fanboy), Nika Futterman (Chum Chum)The eponymous, hyperactive duo, who live by the rule of no work and all play. They spend most of their free time hanging out in the local convenience store or having all kinds of wacky adventures in their house, which lacks any kind of adult resident. They are both comic book nerds (although much less so than Oz) and get ecstatic about the tiniest things.
Kyle the Conjurer (aka, Kyle Bloodworth-Thomason)
Voiced by: Jamie KennedyKyle is a snarky, grumpy kid who, depending on the episode, takes the role of either the antagonist or a tritagonist for Fanboy and Chum Chum. He actually possesses wizardly powers, although no one believes him.
Voiced by: Dyana LiuAn incredibly energetic girl who loves her digital pet Yamaguchi. She is one of Fanboy and Chum Chum's schoolmates. Being vulnerable to all things cute and tiny, she becomes extremely obsessive whenever Chum Chum is involved, often to the point of insanity.
Ozwald "The Oz" Harmounian
Voiced by: Josh DuhamelA nerd who lives and runs a comic book shop with his mother. Considered by Fanboy and Chum Chum to be the smartest human being to have ever existed, due to his excessive knowledge of comics.
Boogregard "Boog" Shlizetti
Leonard "Lenny" Flynn Boyle
Voiced by: Wyatt CenacLike Boog, he works in the local Frosty Mart. Lenny appears to be permanently stressed out/spiritless and absolutely loathes Fanboy and Chum Chum's hijinks. Basically a standard Butt Monkey of the show.
Hank MufflinApathetic Teacher. Speaks with a ridiculously monotone, dull voice and is exceedingly hateful of his job. Sometimes refers to Fanboy as "Purple Kid" and to Chum Chum as "Talking Raccoon".
Voiced by: Candi MiloFanboy and Chum Chum's schoolmate. Appears to be friends with Yo.
Janitor Russ Poopatine
Voiced by: Steve TompkinsThe janitor at Fanboy and Chum Chum's school.
Voiced by: Estelle HarrisShe's... well... Oz's mom. Runs a comic book shop alongside Oz.
The DollarnatorHe has a lot of different skills and abilities that often prove to be unexpectedly helpful for the titular duo.
Sigmund the Sorcerer
Thorvald the Red
Voiced by: Nolan North
Voiced by: Candi Milo