M'kar the Reborn or sometimes called M'kar the Thrice-Born was a Daemon Prince of Chaos Undivided who had once been a Chaplain and then a Dark Apostle of the Word Bearers Traitor Legion, named Maloq Kartho, during the Horus Heresy. In later eras, after his ascension to daemonhood, M'kar became determined to destroy his Legion's old nemesis, the Ultramarines Chapter of Space Marines and their Realm of Ultramar in the Eastern Fringes of the galaxy.
M'kar's true name was Maloq Kartho and during the Great Crusade he was an Astartes of the Word Bearers Legion. Following his Primarch Lorgar and the majority of the XVIIth Legion, he pledged himself to the Ruinous Powers of Chaos Undivided, and became a Dark Apostle (Chaplain) of the Traitor Legion. During the Horus Heresy he took part in the attack on the world of Calth led by First Captain Kor Phaeron, second only to Lorgar in command of the Word Bearers, as part of the Traitor Legion's overall attack against the Ultramarines' Realm of Ultramar. Although the attack failed and Kartho was ultimately slain in battle by the Ultramarine hero Captain Ventanus, he was eventually rewarded by his Chaos masters for all the havoc and slaughter he had caused, and was transformed by the Dark Powers into a Daemon Prince. His hatred for the Imperium of Man and especially for the Ultramarines was enormous and all-consuming.
M'kar eventually manifested in the Materium and in 878.M41 (as the Reborn) he lead a Chaos pirate fleet and attacked Ultramar once again. This time, his fleet was destroyed by a force led by the Ultramarines 2nd Company, Captain Cato Sicarius. Captain Sicarius confronted M'kar in the Helamar Rift and destroyed much of his pirate fleet. M'kar himself managed to escape back into the Warp. In 935.M41, he reemerged from the Warp and led a Chaos force in seizing the star fort Indomitable in Ultramar space, which was then boarded by Ultramarines led by their Chapter Master Marneus Calgar. Calgar defeated M'kar in single combat, but M'kar's hatred of the Imperium and Ultramar was so strong that it was not possible to banish him to the Warp, even with the help of the Inquisition. The best the Imperials could do was bind M'kar to the Warp core of the star fort; this ingenious bond meant that every time M'kar struggled to escape into the Materium, he would be pulled tighter within the core. The star fort, garrisoned with fully half the 5th Company of the Ultramarines, was then ordered to plot a secret course through the remote, uncharted areas of Ultramar. The fate of M'kar was kept secret: possibly fearing that someone might eventually seek to free him, the "official" Ultramarine version of the battle was that Chapter Master Calgar had torn M'kar "limb from limb" and sent him reeling back into the Warp. M'kar was next involved in action against the Blood Angels in 965.M41 and specifically sought out their Chief Librarian Mephiston, who he unsuccessfully tried to turn Renegade while the Librarian was trapped by the Daemon Prince in the crystal caves of Solon V. Mephiston rejected his captor's claims and throttled the life out of M'kar. In 997.M41 M'kar transformed the entire Agri-World of Sondheim V into his private daemonic pandemonium. Shortly after, Hive Fleet Leviathan descended upon the planet, and the Sky Sentinels Space Marines Chapter was dispatched to reclaim it. However, upon seeing the extent of the situation as the Tyranids battled the Forces of Chaos, they opted to call in an Exterminatus.
- "The inferno of my vengeance fills you! It will burn you, my bearers of the holy word, it will fill your veins with power and fire until Ultramar is in ashes. As my power flows in you, so too will I see what you see, feel what you feel and know what you know. With each death I will grow stronger. With every fortress burned my reach will stretch further. You will be my army of dark righteousness. You will be the Bloodborn and your name shall strike terror into the hearts of men! Spread throughout Ultramar and take my fire to the Ultramarines! Burn them from their fastnesses until no trace remains. This is my holy word!"
- — M'kar the Thrice-Born
Approximately two standard years later in 999.M41, Chief Librarian Tigurius of the Ultramarines had a vision which foretold the reappearance of M'kar as the destroyer of Ultramar, although he did not know who the vision truly foresaw save that it would be an entity called the Thrice Born. The truth was revealed when the Iron Warriors Warsmith Honsou discovered the secret of M'kar's imprisonment, and after finding and conquering the Indomitable, set him free as his ally in a new Chaos campaign against Ultramar. Possessing a desecrated Dreadnought shell to remain in the Materium, the newly rematerialized M'kar bound the Indomitable to a Warp Gate and called forth a huge army of daemons, who along with others under his command he named the "Bloodborn." M'kar eventually faced Calgar on the planet Talassar, but his essence was completely annihilated after Calgar struck him with the Shard of Erebus, the same blade that Captain Ventanus had used to slay M'kar's human form of Maloq Kartho on Calth during the battles of the Horus Heresy.
- Codex: Blood Angels (5th Edition), pg. 16
- Codex: Grey Knights (5th Edition), pp. 14-17
- Codex: Space Marines (5th Edition), pg. 40
- Codex: Tyranids (5th Edition), pp. 28-31
- Battle for the Abyss (Novel) by Ben Counter
- The First Heretic (Novel) by Aaron Dembski-Bowden
- Know No Fear (Novel) by Dan Abnett
- Iron Warrior (Novella) by Graham McNeill
- The Chapter's Due (Novel) by Graham McNeill