Everyone knows the story of Johnny Blaze. A daredevil motorcycle rider, he sold his soul to the devil in order to buy his dad a little more time on earth. The devil kept his end, and then came to demand his due. Johnny found himself saddled with the demon Zarathos, the true Spirit of Vengeance. When innocent blood was spilled, and the guilty walked free, Zarathos took control of Johnny, and transformed him into the Ghost Rider. A being of fire and bone who felt no fear, no pity, and who would not stop until the guilty had been punished.
Johnny Blaze wasn't the first to bear the curse of the Rider, and he was far from the last. While each iteration of the Ghost Rider changes in appearance, and in methods, the embodiment of Zarathos always has a set of signature abilities, and a single, driving goal. Vengeance. And it will not stop until it has fulfilled its purpose.
If you'd like to bring the Rider to your Pathfinder game, here's a simple guide to get you started. Additionally, if you'd like to see other characters from the Marvel Universe, like the Avengers, in addition to the cast of Game of Thrones, or Gotham City's villains and vigilantes, the Character Conversion page on Improved Initiative has you covered.
Attributes, Race, and Traits
Most of the people who have played host to Zarathos for any length of time have been human. Though that isn't a requirement by any means (and a flaming orc skull would be pretty awesome), humans have been the demon's favored host. When it comes to your attributes, your primary consideration should go to your Charisma score. After that, you need to decide whether you're attacking with Strength or Dexterity. Wisdom should also be as high as possible, if you have a good number left. Your Constitution, for fairly obvious reasons, won't be a concern.
As to your traits, you need to ask if you're re-creating one of the existing hosts (Johnny Blaze, Dan Ketch, etc.), or if you're making your own. Traits that will serve the Rider well, though, may include Deathspeaker (+2 trait bonus on Diplomacy checks when dealing with Undead, and +2 on Charisma checks to influence the Undead, as with Command Undead), or Demoralizing Presence (+2 trait bonus on checks made to demoralize opponents). Other fitting traits might include Oathbound (+2 bonus on Will saves against Charm and Compulsion effects), Demon Smiter (once per day, gain a +4 bonus on a single attack roll while fighting demons), or even Vindictive Strike (once per day, gain a +1 trait bonus to attack against a creature who just hit you).
Class, Feats, and Skills
The obvious choice for Ghost Rider is the cavalier archetype of the same name. These cavaliers gain the service of a spectral mount, which manifests in ectoplasmic form. They also gain immunity to fear, and Frightful Gaze, which is a gaze attack that leaves enemies paralyzed with fear on a failed save. It may not be quite as powerful as the penance stare, but it's a good stand-in, since it can be done at-will (though a creature that saves is immune for 24 hours).
Also, the obvious choice for your cavalier order is going to be the Order of Vengeance.
When it comes to your skills, you're going to want Ride, Sense Motive, Intimidate, and Diplomacy. If you can spare the skill points, Perception, and Knowledge (planes) or Knowledge (religion) would also be appropriate areas of learning for the Rider.
When it comes to feats, you have a lot of options to choose.
For example, if you're planning on exacting vengeance from the back of your mount, then you're going to want to have Mounted Combat (Core Rulebook 131), Ride-By-Attack (Core Rulebook 132), and Spirited Charge (Core Rulebook 134). You won't have to spend feat slots on the first two, though, as you'll see in the next section.
If you want to wield the signature chain that Ghost Rider is often pictured with, you're going to need Exotic Weapon Proficiency (Spiked Chain) [Core Rulebook 123]. While it isn't a reach weapon anymore, you could choose to wield a small-sized version in one hand (though it would take a -2, and there's nothing saying you can't swing a two-handed weapon from your mount). You might want to consider, instead, using a scorpion whip. If you go that route, you should invest in the Whip Mastery (Ultimate Combat 123), Improved Whip Mastery (Ultimate Combat 106), and Greater Whip Mastery (Ultimate Combat 103) feats in order to really put that weapon to work.
You may also want to take Dazzling Display (Core Rulebook 120), Shatter Defenses (Core Rulebook 133), Disheartening Display (Advanced Class Guide), and Violent Display (Blood of The Moon).
Adding a Template
This guide, so far, has been useful for players who are looking to emulate the skills of a host, or former host, or the Rider. However, this isn't a guide for playing Johnny Blaze, Dan Ketch, or any of the others who once wore a saddle for Zarathos. It's about bringing the sheer power of the Ghost Rider to the table. And that is not something a player can do on their own without DM approval.
Because you need to apply a template to really bring it home.
The Graveknight template, found in Undead Revisited and in Bestiary 3, is an undying champion. It boosts all your attributes except for Dexterity, gives you bonus feats, a slam attack, and it even ties you to an element (fire, in this case) which you can expel in a cone, which you are immune to, and which you channel through your weapons. They're tough, strong, and nearly unstoppable in their purpose. Graveknights can also take control of undead, which sounds like a fitting power for a character concerned with deciding who lives, who dies, and who gets dragged back to hell. Most importantly, though, a Graveknight is nearly indestructible. Even if they are defeated, the Graveknight's armor begins to re-knit the Graveknight's form, and it rises again in a few days, as whole as it ever was.
Worse, if someone puts on that studded leather jacket, the spirit of the Graveknight might just take over that person, consuming them, and subsuming them into its flaming, vengeful form.
Now, that's a lot of power to put in the hands of a player. It also completely eliminates the former character, which is what makes this build most ideal for an NPC (especially since Graveknights naturally tend toward evil). However, if you have a player you really trust, then you might be able to tie these abilities to a possession effect, essentially granting the character cursed with the Rider the ability to take on this template when appropriate. It remains, however, ridiculously powerful if put in the hands of a PC.
What's Your Story?
The legend of the Ghost Rider has changed with every host who has worn the flames of Zarathos. How did you acquire it? Are you trying to rid yourself of the condition? Do people even know who you were before you rose as the avatar of vengeance, mounted on a nightmare as you hunted down those you deemed deserving? Were you a good man in a former life, who is now little more than a hanging judge? Or were you so bad that even death didn't want to lay its hands on you?