There are rumors of a place beyond merely mortal perceptions — a place past the pale pleasures and common agonies of our world, where strange beings will allow your consciousness to transcend the normal, and the accepted, into realms undreamed of. Those who find their way to the gates of this realm, though, find hell more often than they find heaven. And the creatures that oversee this place of torment, the bloody-handed sadists whispered of by those who know, are called many things. Angels, demons, surgeons... and cenobites.
The most infamous of the cenobites, the prince of agony, is known far and wide for his horrific scars, and for the nails driven deep into his skull. There are some who call him Pinhead... a name the creature detests. Those who dare to utter that name in its presence often regret the decision, and wish they had shown more respect to the infamous hell priest.
A terrifying figure on his own, and horrifying as the head of a cabal of other cenobites, Pinhead is a legend. If you've been looking for a chance to bring him to your Pathfinder table, this guide should get you started. However, it is worth noting that this guide takes elements of the character seen in the novella, The Hellbound Heart, and in the novel, The Scarlet Gospels. If you're more familiar with the film version of Pinhead, particularly from the second film onward, where his background and human nature are specifically laid out, you will not find those elements present in the guide below. If you prefer that version of the character, however, you can add those elements in with little difficulty.
Attributes, Race, and Traits
While it's unclear what Pinhead is, precisely, he is often referred to as a demon. We'll get to that. For the time being, though, use "human" as his base race. This gives you an extra feat, bonus skill points, and all the other stuff we love about humans. As to his attributes, you will want to focus on his Wisdom and Intelligence, followed by his Charisma. Constitution is good to have, and assign the higher stat to Strength or Dexterity, whichever you feel would be a better attack stat.
When it comes to traits, there are a lot of good options to choose from. Acolyte of Apocrypha (gain access to cleric subdomains you might not normally have) is a good place to start. You might favor Bruising Intellect (substitute your Intelligence modifier for your Charisma modifier when making Intimidate checks) if there's a gap between your Intelligence and Charisma scores. You should invest in Magical Knack (gain a +2 trait bonus to your caster level in a single class), though, since you'll definitely be blending magics.
Classes and Domains
Pinhead is, first and foremost, a member of the Order of The Gash. This infernal monastery is where the cenobites congregate, where they reflect on the divine agonies, and where creatures like the Engineer often lurk, deciding who will suffer, and who will rise into the ranks of the Order.
So, the hell priest's most likely class to begin with is cleric. It's also the class that should be selected with Magical Knack, because even when he gains other, forbidden knowledge, he is still most skilled with the powers granted to him by his membership in the Order. The most obvious domain to grant him is the Kyton domain. If you wish to make the Pinhead we see in The Hellbound Heart, this would be his only class, as he derives his power entirely from the depths of hell. A solid secondary domain is Nightmare, though at least part of the decision will come down to what gods and devils grant power in your setting.
The next class to add on is wizard, since in The Scarlet Gospels, Pinhead made it a point to track down the mortal world's magic users, and torture the secrets of their magics out of them. Forbidden lore to a member of the Order, Pinhead learned in secret, and gathered the grimoires and tomes of those he tortured and slew to build his knowledge. This makes a universalist wizard an ideal choice, and though Pinhead has no items of significance that fit into the bonded item category (unless you were willing to count his nails as said object, taking up the head slot), it would be simple enough to work an amulet into his bloodied garments.
Once you can cast both arcane and divine second-level spells, it's time to start taking levels of Mystic Theurge. This class dovetails the two areas of Pinhead's learning, and allows you to draw on a massive number of spells.
Skills and Spells
Skill points are always at a premium, but Pinhead's are pretty focused. Knowledge (arcana), Knowledge (religion), and Knowledge (planes) are definite requirements. Heal, Use Magic Device, Intimidate, and Spellcraft are just as important. If you have spare skill points after that, Sense Motive wouldn't be a bad skill to have ranks in.
As for spells... well, you have access to the entire cleric list, and you can pick a slew of things from the sorcerer/wizard list. So, rather than provide an exhaustive detailing, here are some suggestions for investment.
Barbed Chains is perhaps the only required spell, as it's something of a hallmark for the cenobites. Planeshift is something we see them do with some regularity, as is Dimension Door, or any spell that allows shadow teleportation. Hedging Weapons is useful if you want to cast freely in combat. Which spells you take other than these will depend on what task you're setting your Pinhead to. If he's opposing champions of good, then you'll want to make use of Protection From Good, as well as illusion spells that prevent Pinhead from being easily harmed in combat. If, on the other hand, he's being sent to harass individuals causing trouble for his masters, then transmutation spells will allow him to buff himself up, and to disfigure and cripple his foes before they have a chance to fight.
We don't see the infamous Cenobite using much magic, as he is often dealing with average mortals, so there are few restrictions on the spells that fit the concept, except that it is unlikely he draws them from good-aligned sources.
Feats and Equipment
Most of Pinhead's power comes from the supernatural forces at his beck and call. However, the right feats can enhance that power significantly. These are suggestions, but DMs should feel free to alter them depending on their play style and needs.
The first feat you should take is Eschew Materials, followed by either Warrior Priest, or Combat Casting. It might not seem that big of a deal, but we never see Pinhead's power fail because someone pointed a knife at him, and we never see him pull out rust monster phlegm from a belt pouch to make his chains appear.
Additionally, it's a good idea to determine which school the majority of the spells you personally use most come from, and invest in Spell Focus, and Greater Spell Focus. If you believe you will be using Pinhead to fight creatures resistant to magic, then it's also a good idea to invest in Spell Penetration, and Greater Spell Penetration to make up for his multiclassing.
As to his equipment, well, Pinhead doesn't seem to bring much into the field with him. His bloodied raiment could easily be a black Robe of The Archmagi, allowing him to access the magic item's power through his wizard levels. A Perilous Puzzle Box would be thematically appropriate, but it would give little value unless it acted as a trap to call Pinhead's attention to a certain location. He carries a sickle, as well as an apron of butcher's tools, but we almost never see him use them. They simply signify his status as a brother of the Order, and only go to work when there is a subject before him.
Add A Template
Up until this point, the guide could be used by pretty much any player who wanted to play a tortured worshiper of a dark deity. What takes Pinhead out of the realm of player characters, though, is that he requires a template to really put the icing on the cake.
That template is the Apostle Kyton.
Formed from the tortuous agonies inflicted on mortals, apostle kytons are those who embrace the horror being done to them, twisting their bodies and souls into something more powerful than they were in life. They gain darkvision, immunity to cold, spell resistance, and regeneration. They also gain a Bleeding Touch, Agonizing Prayer, an Unnerving Gaze, and a Seductive Oration. The last one might as well be renamed We Have Such Sights to Show You.
While there's technically nothing stopping you from allowing players access to monster templates, it's really not a good idea to do it, especially with something as powerful, and as inherently evil, as the Apostle Kyton.