Be'lakor the Dark Master is the first (and depending on the setting, debatably only) Daemon Prince of Chaos Undivided at the time. Of course in 40k, this claim of "Only" is suspect with the unclear status of Lorgar and Perturabo's alignments, as well as whether Nemeroth's still alive. In Fantasy and AoS he is so far the only undivided Daemon Prince (except for non-canon material). His name likely derives from the name "Bellator", which means warrior in
Latin High Gothic.
Due to his nature as a daemon prince of chaos, he's been sighted in both Warhammer Fantasy Battles as well as Warhammer 40,000. In both, he began as an ancient warlord from ages past who fought in the name of the Chaos Gods before they decided to elevate him as a Daemon Prince. Then he got cocky, thought himself better than his four owners, and then got royally bitchslapped back into line.
Be'lakor was one of the earliest Chaos warlords, leading vast hordes of Daemons to ravage the world long before the Elves rose up against them. He impressed the Chaos Gods so much they turned him into a Daemon Prince, the first time they ever did that to a mortal follower of Chaos Gods. However, his four parents began bickering for ownership, each offering some presents in exchange for his loyalty. He decided to then take all their presents and fled to the mortal realms without doing any of their favors. He came during the First Great War Against Chaos, bending many to his will and carving a warpath - unwittingly carrying out the tasks the four set before him. As time carried on, more Daemon Princes were raised, siphoning the power and attention that was once exclusively his and eventually sparking a great war as these new princes sought to carve out territory. This distracted team Chaos from stopping the elves in Ulthuan from creating the Great Vortex, thus stemming the tide of badstuffs spilling into the world.
As punishment, the big four made him become the one to crown Everchosens of Chaos while never getting to become the Everchosen himself, which pissed him off to no end. This is a retcon though, as originally Be'lakor got arrogant and thought he was better than the Chaos Gods, so Tzeentch served him a big piece of humble pie by denying him a physical body and forcing him to crown each Everchosen. At one point Be'lakor co-opted this by possessing one of the Everchosen candidates (who became known as the Shadowlord), but Be'lakor's power destroyed the host body and he was stuck back in the role. In the expansion Shadows of Albion, Be'lakor was the main bad guy there, manipulating people to take the power and artifacts of Albion for himself, before failing and abandoning that plan.
With the latest Everchosen, Archaon, Be'lakor was once again forced to crown the Everchosen of Chaos with the final artifact. Be'lakor played a big part in the Storm of Chaos campaign, but that has since been retconned. Although he still shows up from time to time, he no longer appears to be quite as powerful as he once was, although he is still a Daemon Prince of Chaos Undivided, which is a massive accomplishment in and of itself. In newer lore, he also took the form of a Norse warlord who conducted a raid on a Nordlander town where he raped a woman and fathered a child who would go on to become Archaon.
During The End Times, Be'lakor was all set to return to his former glory and then some, plotting to become the fifth Chaos God by breaking into Kazad Drengazi, the Fortress of the First Slayer (Grimnir, natch), a temple containing the Chaos Gate that Grimnir used to get to the Realm of Chaos in the first place. Be'lakor used the power of the Chaos Gate to break Tzeentch's curse, regain his physical form, and summon four greater daemons, one of each of the Chaos Gods; two of them had had their shit ruined by Gotrek and Felix once before. Be'lakor and his posse planned to backstab Grimnir from behind, at which point Be'lakor would take all of Grimnir's power and ascend to become the fifth Chaos God, but Gotrek and Felix showed up and wrecked Be'lakor and the Bloodthirster, while Grimnir kicked the asses of the Keeper of Secrets, Lord of Change, and Great Unclean One. It looked like Be'lakor and Gotrek's duel could go either way at first, then Gotrek hit Be'lakor with the Bloodthirster and kicked all their asses back to the Realm of Chaos, ruining Be'lakor's plans.
He later caused mischief in Athel Loren by manipulating the Khainites and the more xenophobic forest spirits to attack the elves, but got driven away by the elves armies and the new Incarnate of Light - Tyrion. Though he did play a major role in dooming the world by freeing Mannfred von Carstein from his imprisonment and ensuring the Chaos Gods learnt of Lileath's haven. During his attempt to slay Lileath and consume her divine power, he was stalled by Jerrod of Asareux, one of the last Bretonnian dukes. Jerrod put up a pretty good fight but was no matche for the first daemon prince and had half of his body devastated by the prince. Jerrod did stalled enough time for the arrival of both Malekith and Tyrion, who use their own incarnate magic to capture the big ol' daemon (first Malekith's shadow magic prevent Be'lakor using his shadow trick to escape, then Tyrion use a magical net of light to restrain him). The daemon prince was later interrogated by Alarielle (who is kind to every living being, just not daemons) with various tortures and threatens to turn him into Nagash's guinea pig if he didn't co-operate. Still feeling mischievous, Be'lakor told the incarnates of Archaon's plan in Middenheim just so he could watch them shit their pants. Having trolled enough, Be'lakor was then trapped in a magic ruby by Alarielle for the rest of eternity. One true Everchosen my ass!
Age of Sigmar
Somehow he managed to escape into the new world. While there are hints that he ruled Ulgu before the god formerly known as Malekith rose to power, Be'lakor's first appearance had him get his ass royally handed to him by the Lizardmen dive bombing him with Pterodactyl riders. Embarrassed by this poor showing (which could actually be a reference to a battle in a white dwarf, at the time of lizardmen 7th edition, in that battle report Be'lakor was killed during by being stoned to death by pterodactyl riders), he has since taken into hiding from the spotlight once more. That said, Archaon seems to be following his footsteps, as Archie's been elevated to the "High Marshal of Chaos", which gives him almost free reign to control or kill the champions of Chaos while still claiming no exclusive loyalty to any of the four (now five with the Horned Rat's ascension) - the only difference being that he's still arguably human. In Wrath of the Everchosen, it's revealed he's the Starscream to Archaon's Megatron, forming his own faction of Chaos followers with the (kinda-secret) goal of (eventually) overthrowing Archaon. Despite that, Be'lakor worked with Archaon to defend the Eightpoints against the armies of Nagash, managing to personally slay the Mortarch Lady Olynder (As much as one can slay a Mortarch), sending her soul back to Shyish.
After this Be'lakor set some big plans he had brewing into motion, as revealed in the Broken Realms book revolving around him. He has one of his servants free one of the Stormcast Morathi captured after her ascension to godhood so the soldier can warn Sigmar of Morathi's treachery, an act which ends up distracting the two gods from Chaos' plans. While this was happening Be'lakor went and destroyed some of the Seraphon future scrying devices to blind them and then tricks them into killing one of Archaon's Gaunt Summoners by having them crash the Summoner's Silver tower into Chamon and then nuking the thing thus setting back his rival's plans to use Varanite to breach the Realm gate into Azyr. As an unexpected bonus though the explosion sets off a chain reaction that destroys several Realmgates connected to the Tower and also ends up weakening the fabric of the realms allowing Chaos stuff to seep into reality. This inspires Be'lakor with a new plan to set about nuking other realmgates both in order to cut off the realms from each other and also to allow daemonic forces to pour into reality and overwhelm the forces of order, something which Archaon had never thought to try as he and most of his forces were still technically humans and thus needed the Realmgates to move about on their campaigns. But before Be'lakor can put this plan into action there is an issue he has to deal with first. When he killed Olynder in the Eightpoints back during the Soul Wars, she put a potent curse on Be'lakor that would kill him when the sands in her hourglass ran out.
To deal with this mess Be'lakor took an army to Shyish and used it to track down Olynder, who as it happens was coping quite well with the defeat of her master from the last Broken Realms book. Having figured out how to destroy Olynder - by destroying her body in its tomb in Dolorum, he held his blade over her corpse and the two struck a bargain; he would give Olynder the souls of an entire Stormhost and she would free him from the curse. She agreed and the two attacked a realmgate known as the Golden Gate that linked a city called Vindicarum in Chamon with several other towns, before they then moved on to attack the city itself. The resulting battles end up collapsing the realmgate and causing a Chaos storm that stopped the souls of the Stormcast slain at the Battle of Vindicarum (including that of Lorrus Grymn who Be'lakor personally killed) from travelling back to Azyr thus dooming most of two Stormhosts, the Hallowed Knights and Celestial Vindicators, to utter destruction and leaving their souls to be caught in the Chaos storm, whilst a third Stormhost, the Sigmarite Brotherhood, was completely wiped out to the last warrior, a feat not even Archaon has managed. When Kharadron forces later arrive and use their fleet to evacuate the surviving civilians Be'lakor himself goes to wipe out the fleet's leaders, but the sight of a duardin steeped in ancient godlike power made him decide to retreat (as to who this was bets are it was either an avatar of Grungni or Grombrindal the White Dwarf himself). Having accomplished his goal and deciding not to push his luck Be'lakor then gave the Stormcast souls captured by the Chaos storm to Olynder, who removed her curse from him and left him to his machinations.
Be'lakor makes one final appearance in the Broken Realms saga in the epilogue of Broken Realms: Kragnos where he throws shade at the Newborn twins for their failed attempt at conquering the Ghurish city of Excelsis and their generally lackluster first attempt to make waves in the mortal realms. He also confirms that the duardin he saw at Vindicarum was a god and that the storms of chaos he unleashed at Vindicarum are now spreading to the other realms.
Despite his failure to finish off Vindicarum and Grungni introducing Thunderstrike Armour to counter his cursed skies, Be'lakor has managed to regain a lot of favor with the Chaos Gods and now stands as the first serious threat to Archaon's status as leader of Chaos. While no outright declaration of war has been made, both have sent their forces to raid the other. Indeed, the damage and mayhem he had wrought had proven to be extremely disruptive not only to the forces of Order, who are now scrambling to recover lost ground and rescue their forces trapped in Chamon while Be'lakor's storm persists all the while; but with Archaon once again being disrupted and stalled in his own schemes to break into Azyr, Be'lakor has proven that he is a force to be reckoned with in the Mortal Realms. Well, at least that's what he would like to think of himself, being jealous of his son by rape and all.
In Warhammer 40,000, Be'lakor was the first Daemon Prince, as well as the first (and allegedly "last", but there have been plenty more since) Daemon Prince created through the action of all four Chaos Gods (apparently Lorgar and Perturabo were special exceptions or something (though knowing Pert, I wouldn't be surprised if he was 75% Khornate or something and 0% Slaanesh considering what the Emperor's Cunts wanted to do with Pert)), and quickly proved to be difficult to control even at the best of times. Apparently his creation gave him the Daemonic equivalent of daddy issues and now he spends most of his time trying to kill all other Champions of Chaos, including other Daemon Princes. The Chaos Gods tolerate him mostly because his wild-card status makes him an excellent pawn in their power struggles, something Be'lakor himself is completely unaware of (as he thinks he still has free will and just wants to cement his position as Chaos' sole champion).
Recently, he's shown up to "help" with Abaddon's Black Crusades by giving him seemingly helpful advice that often leads to unexpectedly heavy losses, all in an attempt to undermine his credibility (well, more so than he does on his own). In a stunning display of insight, Abaddon saw through his ruse, but allowed him to remain within the Black Legion in order to keep tabs on him and better prepare for his sudden but inevitable betrayal. The Imperium isn't even that aware that he exists, as Be'lakor has been very careful about concealing his presence from history (with the unwitting help of a Magos who learned just enough about him to know that he exists, but not enough to realize that he's a Daemon Prince).
He's also been shown to be in contact with Ahriman. No word on whether Ahriman has accepted his offer of being made his greatest champion in exchange for his service, however, but seeing as Ahzek rejects even Tzeentch's own offerings to be HIS chosen champion, still thinks he's independent of any god (despite having Tzeentch's mark on the tabletop), and actively tries to become the fifth Chaos god himself, it's a good bet he told Be'lakor to go fuck himself with someone else's force sword.
During Gathering Storm Be'lakor helped the Iron Warriors invade the Imperial Fists star fortress the Phalanx, attempting to upstage Abaddon by using it to attack Terra directly. The Imperial Fists turned the Phalanx's own weapons on the chaos-tainted regions, destroying them and killing most of the Iron Warriors, then the Legion of the Damned arrived. Be'lakor himself got his ass kicked by Tor Garadon (before he was even given a model!). This abject failure was unfortunately the only time Be'lakor was ever really relevant to Warhammer 40k's plot. In general Be'lakor never really is shown doing much and seems to only exist in 40k because daemons in both settings have to cross-over.
During Warzone Charadon: The Book of Fire, Be'lakor arrived having been summoned and supported by the Alpha Legion and Word Bearers working together as best bros. This force invaded the House Raven Imperial Knight Homeworld of Kolossi. The Daemonic and Heretic forces devastated the Imperial forces and successfully captured the world of Kolossi before whisking it away from House Raven and turning into a Daemon World, dishonoring them and leaving them homeless. His forces ended also fucking over Typhus and the Metalica invasion forces. In the end he got shit done, which is impressive in comparison to Abaddon.
A 500pt Monster (literally), Be'lakor is a very expensive but very solid choice for either a Warriors of Chaos or Daemons of Chaos army. He's an upgraded winged Daemon prince with Lore Master in the Lore of Shadow and a 4+ Ward save and any thing shooting at him suffers -2 to hit him to keep him out of the way of any cannons aimed at him. He is very good at making units run for the hills as he has Terror and Unbreakable like a regular Daemon prince but he also reduces the leadership of all enemy units with 12" of him by -1 and if they fail a panic or break test Be'lakor gets an extra D3 power dice for his next magic phase. Finally his sword, The Blade of Shadows is the standard but extremely nasty no armour saves allowed against wounds dealt by it. Over all if you use Be'lakor he'll take up your entire lord slot (unless you play using the last 8th edition FAQ and/or End Times in which case he uses half of it) but he can effectively scare off hordes of enemies and pile drive your opponents lords while also being quite hard to pick off from usual monster killing methods, like artillery.
Age of Sigmar
Be'lakor's combat capabilities aren't really anything special. Sure, his melee capabilities are slightly better than your standard Daemon Prince, and ignoring rend is a neat gimmick (even if its offset by him having a lower save than the standard Daemon Prince. meaning its only really an advantage against Rend -2 weapons). He also heals himself when enemy models flee, but with battleshock being so easy to ignore its not much to speak about. His magic capabilities are better, having a good warscroll spell and being one of the few wizards that can cast twice in Slaves to Darkness. The real thing that makes Be'lakor a good pick, however, is his special rule "The Dark Master".
Be'lakor can secretly pick one unit at the start of the game, which he has secretly been manipulating the entire time. At any time he can reveal his manipulations, causing the selected unit to be unable to cast spells, move, charge, or attack unless they roll a 5+ for the rest of the turn. And of course, you're going to use this ability on the enemy's strongest unit. Need that Frostlord on Stonehorn to kill that one unit on the objective? Need Nagash to cast that combo of spells you need? Too bad.
Be'lakor also has his own subfaction for the Legion of Chaos Ascendant army list called The Legion of the First Prince. It allows lesser daemons to act as meat shields for him and also allows him to reroll hits and wounds if he's surrounded by at least one lesser daemon of each god, but you mainly take it for the command ability which allows him to restore dead models to every Plaguebearer, Bloodletter, Daemonette and Horror unit on the battlefield. Which, due to the way keywords work, include big multi-wound cavalry units like Bloodcrushers and Plague Drones.
His 40k rules are a reworked version of his Fantasy rules which were then super charged. A winged Daemon Prince he has a 4++ invuln save and is Shrouded, and he also has fucking Eternal Warrior so he's pretty hard to kill. The Blade of Shadows is in it's best incarnation as it's a monstrous S+1, AP2, Fleshbane, Armourbane, Master crafted murder stick, he is also a level 3 Psyker with powers from the Telepathy Discipline and he gains a bonus D3 warp charge points when enemy units fail moral tests. For 350 points he's expensive but he's a god damn steal with how killy he can be.
Be'lakor is pretty good in 8th edition. He's very speedy with a 14" movement and gives buffs to all Daemons so works round the restrictions of a regular Daemon prince. He has a -1 leadership debuff and he has 6 attacks. Stack that with his S+1 ap-5 D3 kill sword, he can carve his way through pretty much anything. He also has access to the Dark Heretics discipline which he knows 2 powers from (you will take Death Hex and you will like it) so he is a pretty good all rounder. The only problem is that he needs to be put in his own detachment as he doesn't have any marks of chaos (for some reason) so he can't join a god specific detachment without gimping the rest of the detachment.
This was changed with 9E. Not only does he get all marks as he's supposed to, but also gets a special detachment that allows daemons to work side by side with heretics, though none of them are going to be able to enjoy their full powers and there are certain forces (Daemon princes, greater daemons, specialist marked marines) that are barred from use. Still, making a Chaos army with Deamons and Chaos Terminators is fucking insane. You can also combo with Havocs, Greater Possesed, Vehicles, and even Obliterators.
Scratch that, Be'lakor is very powerful in 9E. Like, Nightbringer levels of powerful. And Nightbringer-levels of expensive- dude's 10 points cheaper. Here's what he's got going for him. First, he's got a permanent -1 to wound, a -1 to hit, and he stops his opponent from rerolling failed hit rolls. Next, he fucks with your units' Ld (-1 to Ld, -1 to Combat Attrition tests) and buffs his own units' shooting and melee. Any non-vehicle unit within 6" of him, with the DISCIPLES OF BE'LAKOR keyword gets to reroll 1s to hit, and he can choose a unit with those keywords within 9" of him to reroll all failed hit rolls assuming Be'lakor is your warlord. Finally, he rerolls all failed hit and wound rolls against other Daemon Princes. His weapon's a giant sword, that can make two profiles. Sweeping Strike is 12 attacks at S8 AP-3 D1, and Piercing Strike is 6 attacks at S12 AP-4 Dd3+3, which ignores invulns. Yes, it ignores invulns. The good thing, is that he brackets. His movement, strength, and attacks all get worse as he loses any of his 16 wounds.
Total Warhammer 3
It WAS implied that Be'lakor was going 9th legendary lord of Game 3 representing the Daemons of Chaos Undivided, however that role has gone to a completely new (and customisable) original Daemon Prince. Be'lakor has been reduced to this new Daemon Princes cackling BBEG, who has kidnapped Ursun after he got struck down by the new Daemon prince (later revealed to be a prince of Kislev who had been sent on a suicide mission to rescue the missing Ursun, but ended up forsaking his faith in Ursun after straying to Chaos) and in taking Ursun to his fun dungeon caused the barrier between the Realm of Chaos and the Warhammer world to be weakened and giving Kislev a reason to counter invade the Realm of Chaos.
- He has a kickass band
- Half of his inner soliloquies is wondering why the Chaos Gods won't notice him.