Ku'Gath was once a Nurgling sitting upon the shoulder of Nurgle. Whilst Nurgle was mixing his most virulent toxin ever, Ku'Gath tumbled from his nesting place into the cauldron, where he took a great draught of the filthy contents and swelled with its power. Invigorated, Ku'Gath drank and drank until the cauldron was nearly empty and he had grown into a Great Unclean One. Nurgle laughed at the antics of his Nurgling, who had become the embodiment of the perfect disease that had been bubbling within the cauldron. Ku'Gath, however, realised that he had robbed his father of the greatest disease ever concocted; and has since been wandering the universe, searching for the perfect ingredients to recreate the toxin for Nurgle. He also captures those whom his diseases corrupt and take them back to his lair, where he can observe their degeneration more closely.[3a]
As the Horus Heresy raged, Ku'Gath was among the Greater Daemons summoned into Realspace by the Thousand Sons, during the Battle for Terra[8a]. After the Lion's Gate Spaceport fell to the Traitors, the Daemons were unleashed to destroy the Imperial Palace's Colossi Gate[8b]. While they succeeded in tearing down the Gate's outer defenses, the Daemons were destroyed by the White Scars' Stormseers and the Adeptus Custodes, before they could complete their task.[8c]
In 927.M41, Ku'Gath was summoned on the Agri-World of Curwen at the head of the Daemonic Legion. A Grey Knights strike force arrived, and Justicar Anval Thawn led a force into the very heart of the Daemonic horde to avoid encirclement. Ku'Gath swallowed the Purifier whole, but Thawn detonated his weapon inside the Daemon's throat and burst from its body. Ku'Gath was slain and banished back to the Warp.
Ku'Gath appears again in 998.M41, when intervention of Justicar Styer and his Grey Knights in attempts of Inquisitor Malia Orbiana to find on the planet Squire's Rest of Sanctus Reach biological weapons against Orks, led to the manifestation in reality the Bonewrack disease - once lost Ku’Gath’s infection. Later the Grey Knight managed to defeat Ku’Gath and his horde of Plaguebearers and expel daemons to the warp. Ku’Gath himself was defeated by the blow of Librarian Gared when his Nemesis Greatsword bisected Ku'Gath's head.
In 012.M42 during the Plague Wars, he appeared on Iax leading seven hosts of daemons, trying to destroy it because of its conversion to a hospital-planet, something that caused death to Nurgle's gifts. During the war on Iax he was given a portion of Nurgle's own cauldron, which he attempted to use to concoct a brew that could slay Roboute Guilliman. Ku'Gath's plan later came to a head at Parmenio, where the Daemon failed to kill Guilliman who instead slew his lieutenant Septicus.
Despite the setback on Parmenio, Ku'gath was able to use some blood he gathered from Guilliman there to complete his ultimate disease: the Godblight. Going against Nurgle's own orders to withdraw to the Scourge Stars in order to wage the War in the Rift, the Great Unclean One instead sought to earn greater glory by remaining in Ultramar and continuing his alliance with Mortarion.[10a] Upon Iax, Ku'gath sought to use Nurgle's cauldron in combination with Guilliman's death in order to move all of Ultramar into the Garden of Nurgle, but was foiled when he was assailed by an Imperial strikeforce of Space Marines and Cadians led by Colonel Odrameyer. Ku'gath was able to defeat all the Space Marines but was slain when Odrameyer rammed his Leman Russ Battle Tank into the Daemon and delivered a point-blank Power Sword strike directly into his skull. Moreover, his portion of the Cauldron of Nurgle was destroyed thanks to the efforts of the Militant-Apostolic Mathieu.[10b] Due to this and his prior insubordination, Rotigus would inform the still-regenerating Ku'gath in the Warp that both he and Mortarion had earned Nurgle's ire. Ku'gath would not be able to re-manifest into the Imperium for quite some time, and even worse had lost his status as the most favored of Nurgle's Daemons.[10c]
Unlike his fellow Great Unclean Ones, Ku'Gath is a sombre creature. He is also studious and observant, all the better to create the perfect disease. He is pessimistic and prone to worrying, bemoaning Nurgle's plan on Iax as likely to fail. Unlike most Daemons of Nurgle he despises music, and violently demands that the twisted bands of the Plague God keep silent while around him.
Despite his formidable powers, Ku'gath does not enjoy fighting and usually attempts to avoid scenarios where he would have to personally battle.[10a]
Ku'Gath rides atop a palanquin carried by straining Nurglings, and loaded with the paraphernalia of his mobile laboratory. In battle, Ku'Gath uses the opportunity to conduct his field tests, unleashing clouds of spores and bacteria that could wipe out whole armies.
- 1: Battle Missions, p. 17
- 2: Codex: Grey Knights (5th Edition), p. 16
- 3: Codex: Chaos Daemons (6th Edition), p. 51
- 4: Sanctus Reach: Maledictus (Novella) by David Annandale, Chapter Ten
- 5: Dark Imperium (Novel) by Guy Haley, Chapter Sixteen
- 6: Dark Imperium: Plague War (Novel) - Chapter 3
- 7: Warhammer 40,000 8th Edition Rulebook pgs. 154-159 - War Zone: Ultramar
- 8: Saturnine (Novel)
- 9: Warhammer Community: Warhammer Preview Online: Black Library (posted 12/5/2020 – Interview with Guy Haley (last accessed 12/5/2020)
- 10: Godblight (Novel)