Johann van Hal
Johann van Hal is one of the most infamous Witch Hunters in the Empire, driven by a deep, desperate need for atonement. See, he is the last of the cursed van Hal bloodline, a dynasty disgraced by the fact that one of their ancestors, Frederick van Hal, became a powerful necromancer under the command of Vlad von Carstein during the Skaven Wars. Yeah, the guy who invented Vanhal's Dance Macabre? That's this dude's great-something-granddaddy. Ever since then, every scion of the van Hal family has tried to prove their dedication to Sigmar by battling witches, warlocks, mutants, beastmen, the undead and every other 'orrible whatsit associated with the ruinous powers of dark magic and/or Chaos.
Unlike most witch hunters, Johann tends to act as a mercenary, wandering the Old World in search of battles against the forces of darkness to fight. He does so in the company of his sole friend; the Sigmarite warrior-priest Wilhelm Hasburg, who saw his temple burned by Chaos worshippers and some whisper was left more than a little nuts by seeing his life's work go up in flames. Mutilating yourself to express your piety and ceaselessly prophesying the end of the world tends to leave that impression with people, don'tcha know? Still, his devotion is unquestioned, and Sigmar still answers his prayers.
When facing supernatural foes, many desperate generals draw the Mark of the Hammer on road signs and town gates, calling the legendary Witch Hunter to come to their aid. Johann will offer his services to anyone who is willing to pay. All the gold that he does not need himself is donated to the church of Sigmar. So when the forces of Undeath threaten or the darkness of Chaos falls upon the Old World, Johann van Hal and Wilhelm come. They face the most terrible foes without fear, and attack foul Undead orterrifying Daemons with cold fury and hatred burning in their eyes. After the battle they claim their prize and depart without a word - and most men are happy to see them go.
On the tabletop, Johann and Wilhelm act as a Dogs of War Regiment of Renown that can be hired by Empire, Dwarfs, High Elves, Wood Elves, Lizardmen and Dogs of War armies as a Rare choice for a cost of 350 points (200 for Johan, 150 for Wilhelm).
Johann has Movement 4, Weapon Skill 5, Ballistic Skill 5, Strength 4, Toughness 4, Wounds 2, Initiative 5, Attacks 3, and Leadership 9. He's armed with two pistols loaded with Silver Bullets (so his shots count as magical attacks) and he wields the Stake of Sigmar; a two-handed weapon that doubles Johann's Strength to 8 when fighting Undead or Daemons and automatically kills any vampire it delivers so much as a single unsaved Wound to, which they can't Regenerate either!
Wilhelm has Movement 4, Weapon Skill 4, Ballistic Skill 3, Strength 4, Toughness 4, Wounds 2, Initiative 4, Attacks 2, and Leadership 8. He carries a Holy Staff adorned with a jawbone that Sigmar reputedly used to singlehandedly massacre an army of Sakven; it grants him +2 Strength in hand-to-hand combat and automatically wounds Skaven, Daemons and the Undead. He also has all the special rules for a Warrior Priest of Sigmar.
Both characters always fight together and are treated as a unit of skirmishers that cannot join or be joined by other units or characters, though they also count as a single man-sized character for the purposes of not being targeted by enemy missile fire. They also have the common trait of being Immune to Psychology, with the exception of Hatred (Chaos, Skaven, Undead). Neither character wears any armor, so watch out for getting hit!