Dullahan

 The best thing that blogs and articles that existed far before this one did for fantasy RPGs is push forward the idea that encounters with sentient undead shouldn't just be combat - they should each contain a mystery, a fixation, making the why of the fight as interesting as the how.

Regalt of Greevia was a witch-hunter in life. In death, not much has changed- but while his methods were violent in life, he never hurt anyone he believed to be innocent. These days, his infamous catchphrase "Nana, give me your head" is dreaded across the world, as it means torture and even slaughter of anyone who might know anything begins until the witch, hag, or changeling is brought to him for execution. All the while, the warlock who arranged his execution hides his head somewhere halfway across the world...

The Pastor is a dullahan dressed in a priest's black robes who rides across the western plains. Whenever he encounters travelers, he asks them for a confession. Most are swiftly judged - but for some unknown reason, those whose stories are about sins in the service of a greater good are spared.

The Third Inquisition is known for using any means necessary to get results. For instance, years ago they found an undead warrior's severed head, and he has proven to be one of their most valuable assets. Unfortunately, their over reliance on the dullahan comes back to bite them - as the said head turns out to have been a Lich's phylactery the entire time. Coming in conflict with the lich, the choice to destroy the head is obvious - but that means absolutely infuriating the dullahan, who not only is an extremely capable combatant, but also knows far too much of the inquisition's secrets.