M'kar the Reborn is
a Daemon Prince of Chaos Undivided and the biggest failure since Abaddon as well as Matt Ward's favourite whipping post DEAD. His history of defeats reads like a who's who of the Imperium queuing up to bitch slap him. His one notable achievement is banishing Kaldor Draigo to the warp. So Chaos can thank him for autistic murderhobo running freely in the warp and skullfucking daemons on sight. How this makes any sense when he has been repeatedly and humiliatingly defeated by lesser combatants is unclear, except for bad writing.
According to Graham McNeill's Ultramarines novel series and Dan Abnett's Horus Heresy novel Know No Fear, M'kar was once Maloq Kartho, a Dark Apostle of the Word Bearers. During the Horus Heresy, Kartho participated in Kor Phaeron's assault on Calth, one of the worlds of Ultramar, where the Word Bearers managed to poison Calth's star to give off extremely deadly radiation that can kill even Space Marines unshielded, and force its people underground. When Kor Phaeron ran like a bitch after getting one of his hearts ripped out by Roboute Guilliman, Kartho was left behind to continue the slaughter of the remaining Imperials. When he realized this wouldn't be possible using conventional means, he started doing niceties like using virus bombs and sacrificing his fellow Word Bearers to the Dark Gods to summon daemons. At some point he was challenged by Remus Ventanus, Captain of the Ultramarines 4th company. During a climactic battle, the enemy commanders faced each other, and through a series of largely forgotten events, the Ultramarine Captain managed to stab Kartho in the chest with the so-called Shard of Erebus.
Despite his complete and utter failure to succeed at his mission, the Chaos Gods posthumously raised Kartho to the status of Daemon Prince of Chaos Undivided, ostensibly for piling up enough bodies to make Calth a new mountain range. While the Chaos Gods can be pretty random with who gets Daemonhood, it's thought that they did it for the lulz, making him the 40k version of the fat chick that gets voted prom queen and doesn't realize it's a cruel joke.
- M31: Contributes to the Horus Heresy by killing a lot of people on both sides and getting stabbed in the chest with a dagger. Inexplicably elevated to Daemonhood by the powers of Chaos. (For the LULs and MAYBE for wasting a few arcologies worth of innocent people.)
- M31(?): Chases Ollanius Pius and friends across time and space for bit, ends up banished by a teenage girl screaming his name. Blood of the Gods, M'kar, we could have accepted getting your ass kicked by Ollanius Pius (honestly, we'd have actually thought a little better of you), but really?
- 799.M41: Attacks Acralem, banished by a young Kaldor Draigo.
- 878.M41: Attacks Ultramar, banished by Cato Sicarius.
- 935.M41: Seizes a star fort briefly, before being torn to ribbons by Marneus Calgar. This was actually a lie, and M'kar was instead bound to the star fort's warp core. Tales of his death are implied to be propaganda.
- 965.M41: Attempts to entrap and tempt Mephiston into Chaos worship. Mephiston retorts by showing he's not afraid to choke a bitch real hard.
- 997.M41: Transforms an agri-world into a daemon world using an artifact, only to lose the world to the Tyranids and the artifact to the Grey Knights.
- 999.M41: Attacks Acralem again, wasted by Kaldor Draigo again. Manages to use the last of his power to curse Draigo to keep him locked up in the Warp until his buddies need him.
- 835999.M41: Back again after what was either an absurdly convoluted plan, or Honsou of the Iron Warriors deciding he would like a pet Daemon Prince to help kill Ultramar. Honsou attacks the star fort with his new army, frees M'kar and tries recruiting him, but Honsou ends up being coleader with M'kar. They attack Ultramar again, with M'kar staying stable in realspace by possessing an Ultramarine Dreadnought and empowered by being juiced by the nearly limitless power of a star fort. Ultra-killed for good by Marneus Calgar (and indirectly by Uriel Ventris who did the legwork) with the very dagger that killed him the first time.
- Added: Turns out the absurdly convoluted plan was a result of Craftworld Iyanden seeing either M'kar or the Smurfs were going to destroy them so they sent them both up to kill each other. So now we can add Eldar puppet to the list.