"Boss" is the common term for the unique monsters that you encounter every so often.
Bosses in the Diablo 3 comes in various shapes and forms. From the randomly generated mini-bosses on a level to Super-unique big quest boss like Diablo, they are all bosses of some description.
There are numerous Champions and random bosses scattered around the game world, while Super-uniques are rarer, and usually set in special, scripted locations or as part of larger encounters.
Bosses / Mini-Bosses
This information is subject to change...
This is the list of random modifiers found on bosses / mini's & super-uniques in Diablo 3.
Cold Aura - This was reported by a fan, but not seen in any videos of the event. It reputedly worked just as it did in Diablo 2, chilling and slowing players within the radius of effect. After Blizzcon, Jay Wilson let it be known that Auras would return to the game, most likely as Monk skills, so monsters having auras as well doesn't seem that unlikely.
Doppelganger - A fairly common boss property; this one allowed bosses to create clones of themselves, much as Baal does in Diablo 2. The clones had the same properties as the boss, and fought just as the boss did. (Making them very dangerous, when they were clones of a nasty boss with a dangerous property.) Fortunately, they had fewer hit points (possibly 50% as much, as Baal's clone does), and their name hovers said "clone of _____" so they were fairly easy to spot. They disappeared when killed, dropping nothing, and all vanished when the boss was killed.
Individual bosses were able to produce numerous clones at the same time, essentially making their own minion packs.
Electrified - Diablo 3's version of Lightning Enchanted bosses, these guys emitted sparks when struck, added lightning damage to their attacks, and presumably resisted lightning damage as well.
Fast - These were much quicker than normal (extremely fast on rare occasions), making the property seem identical to Diablo 2's "Extra Fast" boss modifier.
Frozen - Cold Enchanted. These monsters hit with bonus cold damage that chilled the target, and will presumably have boosted cold resistance as well. They give off a visual clue to their nature, by sparkling with frost and emitting shimmering little puffs of cold as they moved and fought.
Magical - Its effects is unknown. Stay tune for more details.
Molten - Fire Enchanted. A property that adds fire damage (and presumably fire resistance) to monsters. This modifier was also seen on some normal monsters; Molten skeletons were seen, and they appeared to have fire damage added. From this sighting players are speculating that boss modifiers may regularly appear on normal monsters, adding to their abilities.
Mythical - Its effects is unknown. Stay tune for more details.
Nightmarish - A new boss mod in Diablo 3, this one inflicts Horrify, the Witch Doctor spell, during battle. This causes players and their minions to run away in fear for 2 seconds. It's an interesting property, since none of the mind control curses worked on players in Diablo 2. More testing will be required to determine just how dangerous this one is. Would horrified players run into fields of fire, or through a doorway into a room packed with enemies?
That a boss can do this opens the door to speculation that some mind control might work in PvP as well, which would be a very new angle on things.
Plagued - Bosses with this modifier added poison damage to their attacks, and presumably enjoyed greater resistance to poison damage as well. They gave off a visual identifier, with little clouds of green smoke rising up from them. This mod seems to be the Diablo 3 version of Poison Enchanted.
Powerful - Players speculated that it might be the Diablo 3 version of Extra Strong, enabling bosses to hit for extra damage.
Stoneskin - This mod grants the monsters with it higher defense.
Teleporting - Diablo 3 bosses with Teleport used it regularly and randomly; about every 6 seconds the monster would vanish, reappearing at a random location elsewhere on the screen. They did not heal when they teleported, and if they were a melee attacker the boss would charge right back at the character without pause.
Vampirific - These bosses had life leech, and a very high level of it. It doesn't do anymore damage, but the fights took much longer since they were constantly healing themselves. Hard hitting enemies seemed to almost entirely refill their hit points with each successful strike, and some players reported enduring long, tricky battles with these bosses.
"You dare bring the warmth of life into my tomb? Prepare yourself, mortal, to serve me for all eternity!"
The Skeleton King is located in his Throne Room under Tristram Cathedral. He is King Leoric, bound once again to the mortal realm.
King Leoric, later known as the Black King and ultimately the Skeleton King, was the ruler of Khanduras just prior to the events of Diablo I. He was a devout follower of the Zakarum religion of the Light, and was a great lord from outside the country prior to declaring himself king. Though he was a foreign king, the people of Khanduras eventually grew to respect him for his evident purity of heart and deed. He made his court in the abandoned Horadrim monastery under which Diablo's soulstone secretly lay. (Why the monastery in the game appears as nothing but a decrepit church, and why Tristram remains a little village, is not given an explanation.)
However, Diablo's power stirred at the same time, and the Lord of Terror eventually drew the king's archbishop, Lazarus, into the labyrinth under the monastery, where he found the soulstone and was compelled to shatter it. Thus freed, Diablo sought for the most powerful mortal soul he could possess in order to regain his power, and settled for the king's. Leoric found a dark presence trying to intrude into his being, and though he fought it in secrecy, he was not strong enough to banish Diablo (however, Diablo at his current weakened state was not strong enough to fully overtake Leoric, as well), and his mind became twisted and corrupted. As the change began to show in both his appearance and behavior, his own people started calling him the Black King.
The Archbishop Lazarus, also fallen under the power of Diablo, did his best to conceal the nature of the change in the king's person, but eventually suspicions among Leoric's advisors grew to the point that he needed a new plan. Thus, he convinced the now delusional king that the kingdom of Westmarch was plotting to take over and annex Khanduras, manipulating him into declaring war, diverting attention as well as sending many troublesome knights into their deaths when the armies of Westmarch inevitably crushed those of Khanduras.
However, Diablo found that a part of the king's soul still fought against him, and that he would still not be able to take full control. Thus he abandoned his attempts to take over Leoric, leaving him broken and crazed as he much more easily took control of his son Albrecht instead. When King Leoric found that his son had gone missing, he went into a rage and had many innocent people executed for kidnapping the prince. He was eventually slain by his own lieutenant, the knight Lachdanan, who returned from the quickly lost war only to find that he, too, was being accused of the kidnapping, and that the king was nothing but a raving madman who set his other warriors upon those returning.

The Skeleton King is the end boss. Before entering the lowest level of the dungeon, a certain monster would drop the Skeleton King Crown near the entrance. Once the player entered the lowest level, he had to destroy two purple, glowing orbs. While active, these orbs occasionally summoned small groups of monsters to try to stop her. After destroying both orbs, the gate to the Skeleton King's throne room was opened. The player then entered the throne room and clicked on the throne to place the Crown on the dormant Skeleton King. This brought the King to life, beginning the final battle, which included groups of varying types of undead enemies. As long as the King was alive, more groups of monsters would appear after the Wizard had killed the previous groups.
"The Skeleton King had a large amount of health as well as some incredibly powerful swipes with his multi-bladed heavy mace, which left a blurry image as it moved (even when it was stationary)"
However, he moved relatively slowly, making it possible to defeat him eventually with ranged weapons or spells while staying well away from his range, which was rather long despite being a melee attack (mostly due to his large size and the length of the weapon). Once the Skeleton King was defeated, any remaining monsters disappeared, and
"the King dropped several rare items. "

It has been revealed that this boss might have a huge role in the storyline.
"The Mistress of Pain is an arachnid demon and wears a kind of old, torn Victorian Dress and a Head-dress. "
Her face was covered with a veil in her first concept art but another picture reveals just how hideous she really is, as well as detailing some more striking features. Her legs are her most salient feature. She has three pairs of proper legs along with a pair of stingers in the front. The legs do not look like any kind of insect’s legs as they are made of soft flesh rather than an exoskeleton, appearing more like the thighs of a voluptuous woman. Her shins are covered with black stockings decorated with intricate golden demonic designs. Her abdomen is also very soft but is covered by her rib cage, which extends down to cover her entire rear-end for protection. On the tip of her abdomen are spinnerets that spin a very sticky web that can doom unwary victims.
Another, very unusual, feature are the openings seen on top of her abdomen.
"She can lob dangerously toxic projectiles towards her enemies through them."
What other purpose they serve is currently open for debate.
The Mistress of Pain can be half-confirmed to be present in Diablo III as either an Act Boss or a super unique due to the various references to the player in her second, detailed concept art.She has been revealed to have some soft parts which might indicate that the player must be in a certain position to do damage to her. Also notable is the rib cage covering her abdomen, which appears to be breakable to reveal her soft insides that could be easily damaged.
The concept art shows she has a normal slashing attack from her frontal stingers. She can also secrete sticky threads to slow or even stop the player in his tracks. She also has a unique ranged bombardment attack that is released from one of her openings on her back, which drops clusters of damaging projectiles on the player.![]()



The Siegebreaker Assault Beast is the first large boss monster revealed in Diablo III and it blows away all of Diablo II's Act Bosses and Uber Monsters added together, by sheer mass and power.
He is so large that the concept of a single character fighting him is kind of laughable. It is like a mouse taking on a large dog, except that this dog has six legs with spikes on the front two. Of course the mouse has magical spells, armor, and weapons, so maybe it is not such a mismatch after all.
Siegebreaker is purely a melee fighter, with an avalanche of charging and three-hit, punching attacks that deals horrifying damage with the huge blades on the back of his hands. He has some sort of stomp or trample attack as well, one that tears up the earth and creates clouds of smoke from the earth in front of him.
Besides his gargantuan size and speed, the most talked about feature of Siegebreaker's appearance in the WWI 2008 gameplay movie were the fatalities he delivered to two of the four characters fighting him. The most memorable was the death of the male Barbarian, when Siegebreaker picked up the hero and outright bit his head off, then threw down the decapitated corpse with a grunt.
The female Witch Doctor was similarly destroyed earlier in the video, not by a bite, but by being thrown on the ground, after being picked up and howled at. It also seems that the Beast spreads the flames that were present on it, due to an earlier Firebomb attack, on the Witch Doctor, setting her aflame.
Such moves were, as fans rightly guessed, special kill animations and not powerful one-hit-kill moves. It means that the two characters were on very low hit points that the next hit would have killed them. It appears that when the final hit came, the special code of the Siegebreaker made him perform such actions to make the game more lively and realistic, in addition to adding to the gruesome feeling to the game.
This confirmation, along with the fact that other bosses will also boast such kill animations and even near-kill moves, brings a question: do other non-boss monsters also have such talents? That is, will the players witness a variety of death animations when their characters are killed? For example, shattering to iced pieces when frozen, burning to the ground when burnt, being charred to bones from lightnings and so on? As of this, there has been no confirmation.
After her death, the Witch Doctor's body lies in the small pool of water, before the temple from which the Beast emerged. Her body is later struck by another attack from the Siegebreaker, flying away, never to be seen again in the video. The Barbarian's corpse was thrown to somewhere far away and is never seen again either.
Siegebreaker's death animation; he crumbles down to pieces in a very pretty way, like a decaying, hollowed volcano, but then sends out five jets of red light, which swirl around the screen for a moment before crashing to earth. Where the lights land, in the cemetery where the battle took place, great numbers of Skeletons spawn. It's not clear why a giant centaur-dog beast like Siegebreaker would spawn human skeletons when he dies. It is sometimes speculated that those were the remains of the victims that the Siegebreaker had devoured.



Thousand Pounder is a special boss monster; He is seen in the Old Cathedral beneath Old Tristram.
Summoning Ritual
Thousand Pounder is summoned up in a scripted event. The Barbarian in the gameplay demo is running through the dungeon, when he comes upon a circle of five Dark Cultists channeling their energy to call up a demon. At first there are three pale-skinned youths dancing in the circle. They explode one by one, and then from their blood and flesh the demon is conjured.
While the Barbarian watches, lights began to glow and the Thousand Pounder takes form. First his bones appear, then muscles, then skin over the top, until with a final explosion that sends the Cultists flying, Thousand Pounder bursts into life.
Once he is ready to rumble, Thousand Pounder moves slowly, but has tremendous power, and deals heavy damage with his two large maces. When his health drops below about 50%, he kicks into a turbo mode. At that point his tattoos begin to glow red and he moves much more quickly. When he is defeated his death animation is basically the summoning animation in reverse; his skin sloughs off, then his muscles, before his bones clatter to the ground.

"The other way we emphasize monster character and personality is to look at the monster on whole. How do they get on screen and die? He's going to be on screen in a cool way, so we went to the Thousand Pounder here. He's all 'bout hell. He's summoned from it literally piece by piece. When he gets on screen we figured he should be mad and big. Express anger. Part of his gameplay is that he gets really mad when he's almost dead. Throws a huge temper tantrum and this changes how he plays and how the player has to play against him. When he's enraged we changed how he looked; made his tattoos glow, gave him new attack animations and special effects. When he dies, the animation is somewhat a reverse of how he came on screen. We did this to show off the whole idea that he's from hell."