Sigvald
Imagine Joffrey Baratheon growing up, and gaining the favor of the god(dess) of being a colossal narcissistic asshole FOR being a colossal narcissistic asshole along with a demigod powers, and an army of sick fucks. That's who's the Sigvald is.
Sigvald was born from an incestuous relationship between a powerful warlord and his sister. Sigvald was beautiful from birth, save for a horned birthmark on the back of his neck, and was spoiled by his father until expelled from his tribe by his father due to his "fondness for human flesh". Sigvald proceeded to murder his father in his sleep and departed for the Chaos Wastes, earning Slaanesh as his patron. Now, Sigvald marches at the head of an army devoted to himself, eradicating anyone he deems to be ugly, crude or irritating.
Sigvald has burned down cities on a whim; one story suggests that he destroyed the town of Chamburg because the wine there was not to his taste. Other exploits include declaring war on a province of the Empire because he once broke a nail on a warrior priest's armor during a previous battle and heading to Ulthuan to scalp as many High Elves as he could because their hair was prettier than his/they were more renowned for pretty hair than he was.
He is spoiled by Slaanesh and is described as being extremely self-centered: his body-guards bear mirrored shields so that he may preen himself in the midst of battle. His gifts from Slaanesh have left him beautiful on the outside, but rotten inside. The ground literally reshapes itself for him and his feet float and inch above the world's surface. He wears an armor of ensorcelled gold that never rusts or gets dirty and fights with Silverslash: a rapier of silver forged from the sword of Slaanesh.
He appears a few times in the end times, first ravaging kislev. After this he makes his way to bretonnia where he heads the siege of Parravon. His forces overwhelm the grail knights, forcing Gilles to retreat but not before he kills sigvalds right hand man. He takes a break from fighting and turns parravon into his own personal par aside, feasting on the finest flesh bretonnia has to offer. Much to his dismay, the chaos gods pick him up and put him in Middenheim, where he is one of the few chaos champions worth a name still living. He throws a hissy fit about not having his mirror eunuchs, and offers mannfred a spot as a replacement. He was one of the warriors tasked with killing valten before he reached Archaon, alongside Valnir and Wulfrik, but lounges on the stairs preening himself while the other 2 duel. He makes an excuse that he doesnt want to fight Valten because he deserves to fight the real sigmar, and prances off to parts unknown. He is still alive during the final battle, leading forces of daemonettes against Nagash' army. He fought Krell in a badass battle in The End Times, and was doing badly at first since Krell is stronger (despite Sigvald being S5 while Krell is S4, though Krell's axe gives him +2S, never mind) and more durable, but Krell cut his pretty face and ruined his sword. Sigvald saw his reflection with the one eye Krell didn't ruin and went absolutely berserk, beating Krell with his bare fists and ruining his perfect hands in the process. After stabbing krell through the eye, he snaps out of it and realizes what he has done. His face is ruined and his hands are ruined to the point where he will never use a weapon again (Someone in GW forgot Sigvald's armor gives him regeneration so wouldn't this fix itself?). While Slgvald sat there crying over his ruined beauty, Throgg snuck in; he'd been ordered by Archaon to work with Sigvald, but Sigvald tried to kill Throgg because of the latter's ugly appearance. In revenge, Throgg smashed in Sigvald's skull then pissed on his corpse. TAKE THAT YOU SLAANESHI NARCISSIST JERK!!