Kheradruakh, whom the terrified call simply the Decapitator, is the great king of the Mandrakes, and his name in the old tongue means He Who Hunts Heads. Among a breed already regarded as living nightmares by the merciless Drukhari, he is a legend darker still, a patron saint of murder revered and feared even by his own shadow-born kin. He holds dominion over Aelindrach, the dimension-warped realm of living darkness that seeps through the underbelly of Commorragh, and from that lightless kingdom he ventures forth to kill.
His antiquity is the stuff of grim conjecture. Kheradruakh has stalked the shadows since at least the age of the Horus Heresy, and some hold that he was once an Aeldari of flesh and blood before his descent into shadow, perhaps the very first of all the Mandrakes and forever the greatest. For eight thousand years he slew with no pattern that any could discern, appearing without warning amid a realspace raid, or hiring out his talents as an assassin for a price paid only in souls. Once set upon a quarry he is inexorable, content to hunt a single victim for decades across a dozen worlds and to lie in perfect stillness for weeks on end, awaiting the one flawless instant in which to strike.
Like all his kind he wears a chameleonic skin of living shadow, and married to his uncanny stealth it renders him all but invisible, able to unfold from the faintest smear of darkness at his prey's back. But Kheradruakh is more terrible even than his fellows. His eye-sockets gape empty and hollow, and a second pair of taloned arms sprouts from his frame, perhaps the gift of some long-ago Haemonculus. His chosen weapon is a straight, black blade that shares his dread title, a sword against which, it is said, no shield ever raised has offered the slightest protection.
Behind the endless slaughter lies a purpose as patient as it is insane. Kheradruakh takes the heads of his victims back to his lair and there strips them to naked bone, shattering to dust every skull that fails to meet his exacting and unknowable standard and setting the rare few that satisfy him into the niches that ring the hemispherical walls of his sanctum. A thousand such alcoves await their occupants, and slowly, head by perfect head across the long dark of centuries, the Decapitator is filling them, hunting toward the completion of some design only he can comprehend.