Summary
World of Warcraftcontinues to expand beyond the retail servers, and the standard Blizzard launcher now includesCataclysmservers andClassicservers, the latter being available in the different categories ofHardcore,Season of Discovery, or regularClassic. Each version has at least a few intimidating raid bosses, and defeating these powerful enemies of those max-level raids continues to be one of the most challenging parts of the game.
Killing the endgame raid bosses is always intended to be difficult, for even the top-rated guilds with the best gear and best players. These days virtually all of the dungeons in every version ofWoWhave different levels of difficulty starting from regular to Heroic, then possibly up to Mythic depending on what version of the game players are in.
Updated on July 25, 2025 by Paul Woodward:Raids have always been where players can find the most challenging PvE content in all of World of Warcraft. Yet with all the difficulties that are available these days in retail WoW, raiding is more accessible than ever before. But for those who want to push their skills and knowledge to the limit, Heroic and Mythic difficulty continue to present challenges that seem almost impossible. Yet no matter what Blizzard throws at players, they always succeed in taking down the greatest threats to all life on Azeroth and beyond. Keep in mind that many of the bosses below are considered based on how tough they were when they were current content.
20Onyxia
The First Taste of Endgame in World of Warcraft
From a mechanics standpoint, Onyxia is not a difficult boss when compared to later raid content added to the game. Yet when World of Warcraft first launched, Onyxia was a challenge that players had to learn how to overcome. In fact, it was mandatory as Onyxia dropped the material needed to make an Onyxia Scale Cloak. Without this cloak, players had no hope of surviving against Nefarian in Blackwing Lair.
Exactly how many attempts there were on Onyxia back in 2004 is unknown, but she was undefeated for 69 days until the US-based guild, Ruined, successfully defeated her. Onyxia may not be the most difficult boss, but at a time when players were still new to raiding, she was a difficult adversary. On top of her fire breathing attack, players also had to be ready for all the whelplings that would spawn and attack the group at the start of the second phase. So while Onyxia doesn’t hold a candle to anything that was released after her, she was once a difficult boss for a playerbase that was new to the game.
19Nefarian
The Final Boss of Blackwing Lair Pushed Players to Their Limits
Blackwing Lair was launched with Patch 1.6, making Nefarion one of the earliest bosses. It didn’t take long for the entire raid to earn a notorious reputation for difficulty, and the end boss, a black dragon named Nefarian, was its savage climax. Aside from some bugs that made the first couple of bosses a roadblock, Blackwing Lair as a raid was a significant jump in difficulty compared to Molten Core or Onyxia’s Lair.
At the end of the raid, players would encounter Nefarian. Fighting this boss successfully took a lot of planning, timing, and just dumb luck. That’s partly why he reigned supreme at the very top of Blackrock Mountain for almost three months before a guild managed to beat him. In addition to having an attack that would kill players who didn’t have an Onyxia Scale Cloak, Nefarian used a unique mechanic called Class Calls where he would call out one of the classes in the raid group and then an avoidable effect would apply to those players, creating an element of randomness to this fight that made it a very difficult encounter.
18C’Thun
Old Gods Are Supposed To Be Tough
Players geared enough to reach the depths of the Temple of Ahn’Qiraj would find the horrific Old God known as C’Thun waiting for them. This monstrous being was one of the most difficult bosses in the game. Between having an eye beam ability that could hit multiple players and constantly spawning tentacles, there was a lot that players had to manage during both phases of this fight.
The exact number of attempts on this unique and terrifying boss is unknown, but it lasted almost four months before it was defeated by Nihilum, a European guild on April 25th, 2006. There are a lot of tough boss fights in both the Ruins and Temple of Ahn’Qiraj, and the battle against C’Thun is one of the toughest bosses in pre-expansion WoW.
17Yogg-Saron
Having No Keepers Assisting Is a True Nightmare
Like C’Thun, Yogg-Saron was an Old God that the Titans had imprisoned countless years prior to the events ofWorld of Warcraft. Anytime one of the Old Gods are involved, players should expect a difficult fight. The unique thing about Yogg-Saron was that he had five separate difficulties based on the amount of Keepers assisting players during the battle. As long as players understood the mechanics and had decent gear, this fight was pretty straightforward.
But on the hardest difficulty, Yogg-Saron proved to be a nightmare of a boss, especially since players would have no way to restore their sanity or kill the adds during the final phase of the fight without the assistance of the Keepers of Ulduar. With the current level of gear that was available at the time, Yogg-Saron was considered mathematically impossible. Ultimately, this belief was proven wrong by a guild named STARZ.
16Ragnaros
Fighting Ragnaros Where He Is Strongest
Ragnaros was a bossin classicWorld of Warcraftwho then was also the final boss of the Firelands inCataclysm. It was not a particularly tough fight nor did it have any unfair or broken mechanics. It was tough because it took most guilds more than 20 minutes to complete, though it wasn’t one of the hardest raid bosses inWoW.
20 minutes is a long time for mistakes to happen, and even one or two party members' deaths could jeopardize the fight in the long run. Focusing for a third of an hour on pinpoint precision and timing is tiring, especially if the raid team has been spending hours trying to master this encounter.
15Lei Shen
A Mogu With the Power of a Titan Keeper
Outside of the Heroic version, Lei Shen is the final boss of the Throne of Thunder raid. Regardless of difficulty, the notorious Emperor of the Mogu was a formidable opponent for raiders back during Patch 5.2. While this fight isn’t anywhere near as long as Garrosh at the end of Siege of Orgrimmar, it was still a brutal boss fight that required every single player to be on the ball.
There were a lot of mechanics going on throughout this fight, and even one mistake could prove fatal to the entire group on Heroic difficulty. Lei Shen also had a very tight enrage timer, which meant that the DPS needed to stay alive and also be as well geared as possible.
14The Lich King
Deadly Abilities Are Expected From The Master of the Scourge
Even though it’s been years since his defeat,the Lich King remainsone ofWorld of Warcraft’s most notorious villains. The prince formerly known as Arthas had been a key player inWarcraft 3and its expansion,The Frozen Throne. Given that he was such an important character, it made sense that he would have to be one ofWoW’shardest raid bosses at that point.
OnceThe Wrath of the Lich Kingexpansion was released, Arthas was back in the spotlight once more. However, it wasn’t until Patch 3.3 that players could finally lay siege to Icecrown Citadel and take the fight to the Lich King. In addition to hitting hard with Frostmourne, the Lich King had a variety of nasty abilities throughout the entire fight. Between Infest, Necrotic Plague, Defile, and then Shadow Traps during Heroic difficulty, the Lich King could easily wipe a raid with little effort. Paragon was the guild that got the world first back then after about 170 tries.
13Blackhand
A Fierce Warrior With Access to Advanced Technology
Blackhand was the final boss of Blackrock Foundry in theWarlords of Draenorexpansion. Blackhand’s first phase usually went easy enough, with a few distractions thrown at players with the Marked for Death debuff for example. When Blackhand fell to 70% health, his second phase would begin with a transitionary explosion, and then every 50 seconds he would summon a Siegemaker which could destroy the raid if not handled properly.
It was a raid that required intense communication and focus as well as knowing exactly what to do at any given moment with all the fire and explosions going off throughout the fight. It’s no wonder it took over 700 attempts for the world’s second Blackhand kill.
12Garrosh
A Tyrant Backed By Dark Powers
Just like Ragnaros in Firelands, the fight against Garrosh is an insanely long encounter. LFR, Normal, and Heroic all consist of three phases with an intermission phase, while Mythic has four phases. Wiping on a boss is bad enough, but then that feeling is made worse when players realize they have to go through this long and tedious encounter again and again until they finally beat it.
Each phase, Garrosh used a unique set of abilities that players would need to be ready for. Garrosh also heals back up to full health at very stage, which is part of what makes this such a long encounter. Not only that, but near the end of the fight, players have to watch out for being mind controlled. On Mythic difficulty, there is a unique phase at the end where players are transported to a ruined version of Stormwind where they have to watch out for a relentless series of AoE attacks while also positioning so that Garrosh gets hit by the Iron Star that he spawns.
11Archimonde
Just As Difficult As He Was Back in The Burning Crusade
Archimonde was the final and hardest boss of theWarlords of Draenorraid Hellfire Citadel, a callback to the dungeon of the same name fromThe Burning Crusadeexpansion.Archimonde’s fight required players to constantly be aware of each other and constantly communicate positioning, as well as random elements that turned the boss fight into a roll of the dice most of the time.
One such random element was the Doomfire spell, a spirit cast by Archimonde that dealt a massive amount of damage to a player for 10 seconds before switching to a new player. The spirit was tough to kill alongside Archimonde, and some raids turned all of their attention to the spirit once it spawned.
