HERO monsters are a core part of the Yu-Gi-Oh! GX series and have been a mainstay in the competitive game for over a decade. HEROES come in a lot of different forms: Elemental, Destiny, Vision, Masked, and Evil being the predominant iterations.
While most of the original Elemental HEROES and their fusions aren't the strongest, Konami has made plenty of incredible HERO cards throughout the years that have warped the competitive metagame. Longevity and overall strength are both factors to consider when figuring out which HERO is the greatest of them all.
Elemental HERO Neos Alius
Elemental HERO Neos Alius is a Gemini monster with the ability to be treated as Elemental HERO Neos if it was Gemini summoned. However, Alius's effect itself wasn't the reason it saw play.
Gemini monsters have an odd place in the game's history, with Neos Alius being arguably the most played of them all. Alius saw play in the HERO Beat deck, where he'd be sacrificed using Gemini Spark and then used as a Miracle Fusion material to summon a powerful fusion monster.
Destiny HERO Diamond Dude
Destiny HERO Diamond Dude has one of the most unique effects in the game. Diamond Dude allows the player to mill one card. If the milled card is a spell, the player can use the effect of the card without paying its costs on the next turn.
In the anime, Diamond Dude was used by one of Jaden's three main Yu-Gi-Oh! rivals: Aster Phoenix. Aster used Diamond Dude for a variety of strategies, but TCG players mostly used him for the chance to hit draw spells or Magical Stone Excavation to gather the pieces for a powerful OTK combo. This deck became known as "Diamond Dude Turbo" and was a key part of the meta at its time.
Evil HERO Malicious Bane
One of the reasons GX is such a beloved Yu-Gi-Oh! series is the Supreme King arc where Jaden falls to the dark side and uses Evil HEROES. In recent years, the game has created a new boss monster for Evil HEROES: Malicious Bane, who can't be destroyed by battle or card effects.
Malicious Bane was a cornerstone of the popular 2020 HERO deck that played an amalgamation of all types of HERO monsters. The monster was difficult to deal with the threat that the fusion spamming strategy could dominate duels with. Not only could it overpower most cards in the game with its effect, but there were few answers for its destruction immunity.
Elemental HERO Prisma
Elemental HERO Prisma allows the controller to send a monster from their deck to the graveyard to copy its name, so long as that monster's name is a material for a fusion monster in the player's extra deck.
Prisma's finest moments actually weren't in HERO decks, he found his main home with Gladiator Beasts. Not only did he grant easier access to Gladiator Beast fusion monsters with his name change effect, but the ability to send Gladiator Beasts from the deck to the graveyard also came in handy.
Elemental HERO Bubbleman
Bubbleman is one of beloved Yu-Gi-Oh! GX protagonist Jaden Yuki's most used monsters, and for good reason. While the anime effect to draw 2 cards was made more situational in the real game, the ability to special summon itself made it a strong card regardless.
Bubbleman saw the most play in HERO Beat, where he was used to help make rank 4 Xyz monsters with his special summon effect. His biggest use was once he was in the graveyard, players could abuse his Water attribute to Miracle Fusion for Elemental HERO Absolute Zero, one of the most powerful boss monsters in the game at the time.
Elemental HERO Shadow Mist
Elemental HERO Shadow Mist was a HERO card specifically made to support the Masked HERO archetype, letting players add Mask Change to their hand whenever he was special summoned. On top of that, Shadow Mist could search for a HERO when sent to the Graveyard.
Until Ash Blossom & Joyous Spring, there wasn't much counterplay to using A Hero Lives to bring out Shadow Mist. It was a brutal combo that made decks containing HERO monsters much stronger. Shadow Mist has seen play in multiple HERO decks throughout the years and even has seen some play in non-HERO decks just for the ability to bring out Masked HERO Dark Law.
Elemental HERO Absolute Zero
Perhaps the strongest HERO fusion monster in the game, Elemental HERO Absolute Zero has the fairly simple requirements of fusing any HERO and any Water attribute monster. For that cost, players can get a 2500 attack monster that can destroy all monsters the opponent controls.
Elemental HERO Absolute Zero was the star of HERO Beat and the sole monster that made the deck viable at its time. HERO Beat could summon a rank 4 Xyz monster with Bubbleman and another hero, then banish both of those monsters with Miracle Fusion to summon Absolute Zero. There were few decks that could keep up after Absolute Zero wiped their field of monsters.
Destiny HERO Destroyer Phoenix Enforcer
Fusion may not have started as the strongest Yu-Gi-Oh! summoning mechanic, but recent revamps in fusion spells have allowed fusion monsters to dominate competitive Yu-Gi-Oh! including Destiny HERO Destroyer Phoenix Enforcer, a brutal fusion monster that can continuously revive itself.
Destiny HERO Destroyer Phoenix Enforcer's ability to destroy cards the opponent controls once per turn while also reviving itself constantly makes it one of the most difficult cards to deal with in the game's history. Phoenix Destroyer is a recent inclusion in the game, but along with Fusion Destiny and Predaplant Verte Anaconda, the new Destiny HERO has completely dominated modern competitive play.
Masked HERO Dark Law
Dark Law isn't a traditional fusion monster. It can only be summoned by a Mask Change card, and the results of the change are terrifying. Dark Law makes the opponents banish their cards instead of sending them to the graveyard, an effect that completely shuts down many strategies.
If there are two things competitive Yu-Gi-Oh! is known for, its graveyard manipulation and searching. Dark Law has effects that cripple both, making him a dominant force in both HERO decks and otherwise. Dark Law is so strong that Burning Abyss and other dark decks have played Mask Change II just to summon him.
Elemental HERO Stratos
Elemental HERO Stratos is a timeless monster with 2 powerful effects. The first allows it to search any HERO monster on summon, and the second lets it destroy opposing spell and trap cards. The second effect is nice, but the first is why Stratos became so powerful.
Elemental HERO Stratos has been the cornerstone of dozens of competitive decks, including game-breaking tier 0 decks like Airblade Turbo and TeleDAD. Stratos is so strong that it was banned for a very long period of time, and has even seen play in competitive decks as recently as 2020.
Destiny HERO Malicious
By banishing a copy of Destiny HERO Malicious from the graveyard, the player can summon a new copy of Malicious from the deck. The effect seems innocent, but Malicious isn't just the best HERO monster ever made: he's one of the best combo enablers in the game's history.
The ability to summon multiple level 6 monsters in a turn has been abused throughout the game's history. TeleDAD, Diva HEROES, and dozens of other combo decks throughout the years have included Malicious as a core part of their strategy. It's no surprise that Konami had to recently restrict Malicious to 2 copies so that players could only use his effect once.