There are countless duelist characters in the world of Yu-Gi-Oh!. Most of them appear for a couple of battles against Yugi, Joey or Kaiba and then disappear after being defeated. While some, like Mai Valentine and Weevil Underwood, become reoccurring characters in the series, others are a little more obscure.
The following five characters are lesser duelists who nonetheless stand out in memory. These cannon fodder duelists might not have had the most complicated and nuanced plot lines, but they stand out as memorable, either due to their strategies, decks, designs or personalities.
It's strange how someone who specializes in dinosaurs, some of the coolest creatures to have ever lived, could be as utterly uncool as Rex Raptor. While initially introduced as a rival to Weevil Underwood, Rex always radiated sidekick "trash-goblin" energy. He was Mai's accessory, then was cannon fodder to make Espa Roba look more dangerous and eventually became Dartz's soul-drained tool. During the entire final arc, Rex's role can be summed up as "Yami Bakura and Zorc do something that ruins Rex's day."
Part of this is how Rex's entire deck is all bark and no bite. Sure, Rex's cards look awesome, but his monsters are weak. Arguably his most memorable moment -- other than losing all the time -- is when Joey beat him and took from him his Red-Eyes Black Dragon. There's something entertaining and endearing about how, despite being so terrible, he keeps on coming back for increasingly petty acts of revenge.
Espa Roba is a faux-psychic with a memorably dorky hairstyle and a gloriously absurd gimmick. Espa claims to be a psychic who can read his opponent's mind to determine which cards are in their hands. Naturally, this is all nonsense. Espa is actually the eldest brother of a sprawling large family, all of whom share Espa's goofy hairstyle. His brothers spy on his opponents from a distance with binoculars and tell Espa what's in his opponents' hands.
Espa's duel with Joey is one of the better early duels in Battle City, in part due to Espa's iconic monster Jinzo. This card ultimately cripples Joey until he figures out a way to destroy Jinzo. While Espa vows to become a great duelist without cheating, he never appears after Battle City. It's incredibly disappointing that we never saw what became of Espa, beyond an epilogue where he confronts Mako Tsunami. There's a lot to Espa's story that lends itself well to a character arc. It's odd that a character like Rebecca Hawkins got a whole season-long arc after her initial appearance, yet Espa disappeared into the aether until one brief epilogue, which ultimately doesn't tell us what became of him.
Bonz is one of Bandit Keith's henchmen during the Duelist Kingdom. Inherently, there's not much to Bonz's personality that's particularly fascinating, but his spooky deck of cards and bizarre, corpse-like appearance are highly memorable. Bonz's ghoulish appearance is befitting his zombie-centric deck. He ends up being one of the toughest duels Joey ever engages in during the Duelist Kingdom. He's a key figure in pushing Joey's character to new heights, and a stepping stone Bandit Keith uses to reach the finals.
Bonz later tries his whole spooky routine on Yami Bakura during Battle City. Unfortunately, Bonz did not anticipate that his ghost tricks wouldn't work on an actual vengeful spirit, so Bakura just took his Locator Cards, along with his friends' cards, and sends them into the Shadow Realm.
Of all the Rare Hunters under Marik and Odion during Battle City, Arkana stands out the most. This former stage magician was disfigured and after a trick gone wrong, and his lover Catherine left him. He joins Marik's Rare Hunters in desperation, with the promise Marik will return Catherine to him.
Arkana wears a flamboyant mask to cover up his disfigurement. He uses lots of magician-centered cards, which makes him in many ways as a dark counterpart to Yugi himself. He even uses the Dark Magician. However, unlike Yugi, he's a cheater. By trimming the edges of his cards in certain ways, Arkana can identify which card is which without looking at them.
Mako Tsunami is one of the most interesting cannon-fodder duelists in Yu-Gi-Oh!, in part because he evolves with every appearance. In his initial Duelist Kingdom appearance, he's just a generic water-themed combatant. His duel with Joey during Battle City, however, reveals him to be a far more complex and honorable figure.
Mako wants to be a fisherman like his father. His card The Legendary Fisherman reminds Mako of his father. He sees it as a representation of his father's great skill as a fisherman. While Mako ultimately loses to Joey, he loses as the only character Joey faced in Battle City -- other than Seto Kaiba -- to not have cheated. While he's a fierce duelist, he's also just a supportive dude who earnestly cheers on the people who beat him without ill will. The anime's epilogue shows that Mako achieves his fishing dream, giving him a surprisingly satisfying character arc for such a minor character.