Zombie Boy is based on the canon character Bonz.
First appeared in Episode 12 - fittingly named 'Duel Of The Dead' - with his friends Sid and Zygor when they were spying on Yugi and his friends. They were helping Bandit Keith to lead the gang into a trap, in which Zombie Boy had to duel Joey in a graveyard themed duel arena. He was called a goth when he scared Joey for the first time. During the duel he appeared to be in the lead while Michael Jackson's Thriller was playing while devastating Joey's life points. His unabridged self cameoed in the duel against the Gay Clown.
He revealed that he dropped out of zombie school which is later revealed to be the Cambridge School for Zombies and was taught by Bandit Keith to become a duelist. He doesn't say anything except "BRAINS", but it is subtitled to be normal dialogue, which might be how the other characters can understand him. (The mummies in The Abridged Movie also had the same voice). In episode 37 it is revealed that in fact he can talk, only saying the word "brains" because that was the only line he got on the script. He also talked in the 3rd anniversary video. When asked why he didn't say "brains" he responded that he "doesn't do that anymore." He's considered to have "the voice of a zombie angel" by Zygor.
He later appeared in Marik's Evil Council of Doom (wanting the free tacos Marik had promised, but later found out they were a lie), and tried to come up with an evil plan that involved eating peoples' brains, but was shot down by Yami Bakura before he could explain. During the evil role call, he made a reference to the "I like turtles" YouTube meme.
In Marik's Evil Council of Doom #2, he thinks that Yami Bakura's favorite movie of all time is gross. Throughout the meeting, he was told by Marik to transcribe everything said. But Marik declared that he be fired for writing the word "Brains" repeatedly. Although Zombie Boy says he did transcribe what they said but was angry to be fired and decided to quit.
Zombie Boy returns in episode 37 apparently hiding in a graveyard were he, Sid and Zygor are stealing locator cards by dressing up as zombies (even though he already is one) and walking to anybody coming by very, very slowly. He gets into a duel with Yami Bakura and convinced that he will win because Bakura is not a main character, after Bakura took them to Silent Hill. Zombie Boy summons his Nemesis from the Resident Evil series only for the creature to fall in love with Bakura's monster (Pyramid Head). After this he surprisingly enough says he quits in English. Zombie Boy somewhat snaps and declares his making a stand (complete with an American flag behind him) about zombies not being respected anymore and replaced by "The Infected" but before he can finish his speech Bakura shoots him in the head with an invisible gun.
He later reappeared in Evil Council #4, joining Dartz so that he can take revenge on Marik. However, even though he speeks normally, Dartz cannot seem to understand him at all, making him unpopular with the other members of Dartz's council.
He apparently enjoys George Romero's old zombie-flicks, but he hates the new ones.