They call him Baba Yaga... but John wasn't exactly the boogeyman. He was who they sent to kill the boogeyman. A legendary assassin with a shadowy past hinted at only by his tattoos, and the whispers told in the darkest corners of the Continental, Wick had left his old life behind. Or, at least, until a couple of young punks decided to break into his house, steal his car, and kill his dog.
You know what happened after that.
If you want to bring John Wick to your Pathfinder table, here's a basic guide to get you started. And if you're looking for other gunslinging hardasses, superheroes, and creatures of the night from popular films, comics, and television, check out the Character Conversions page on Improved Initiative.
Race, Stats, and Traits
John is, like all other folks in the world of the High Table, human. That bonus feat and bonus skill point are going to come in handy, but if you want to tinker with his traits to give him some of the alternative human backgrounds (Dim-Dweller, as an example, would give him bonuses to Stealth, and while the film version of John can't see in the dark, it would be a handy ability to possess for practical reasons), then you should feel free to do that. Dexterity is going to be a prime ability for Mr. Wick, but Constitution, Strength, and Charisma are also nice to have.
As to John's traits, there are a lot of useful ones to choose from. Friend in Every Town (+1 trait bonus on Knowledge [local] and Diplomacy checks) might represent how well-known he is, and all the places he's traveled to in his work. On Guard (+1 trait bonus on Initiative checks, and if you can act during the surprise round you may draw a weapon as a free action) would represent John's extensive training, and carefully-tuned senses. Even traits like Never Stop Shooting (treated as having the Diehard feat, but the only actions you can take when disabled are to draw, load, or shoot a firearm) or Larger Than Life (when you use the Intimidate skill to demoralize a target while you are wielding a firearm, treat your size category as one larger) would make sense based on how we see John perform when in the field.
Classes and Abilities
John is a man of focus. Of commitment. Of sheer will. But where did he get those skills he's honed to such a razor edge?
Well, as far as his background goes, the rumor is that he was once in the military. His tattoo, which translates to Fortune Favors The Bold, is the motto of many military units both past and present. For our purposes, though, the best place to start John off is as a Fighter. Not just any Fighter, though. To represent his extensive use of firearms, of cover, and of modern battlefield tactics, we're going to use the Trench Fighter. This allows you to add your Dexterity to damage done with specific firearms, and it increases the AC bonus you get from cover. You'll still gain weapon training, which should probably go into guns since fighter is the lighter end of the recommended mixture (4-5 levels at most).
Mixed in with the Trench Fighter is the Rogue. Because Rogue levels provide sneak attack damage (ideal for quickly dispatching nameless goons with a quick head shot, or stab to the chest), Uncanny Dodge, a wide array of class skills and skill points, and Rogue Talents that will help round out John's repertoire.
Speaking of Rogue Talents, there are a few you're definitely going to want to invest in. Firearm Training is top of the list, since it gives you proficiency with John's signature weapons. Careful Stab is ideal if you want to recreate the gift of the Baba Yaga, where John cuts or stabs someone in a way that they're disabled, but they will survive if they choose to. Resiliency is also a good investment, since John always seems to keep going long past when he should have laid down and died. Lastly, if your game is using them, Black Market Connections would nicely represent John's membership in the Continental, and how he always seems to have access to the best weapons, armor, and information.
Skills and Feats
John has a lot of skills. While it would be difficult to cover all of them, you're definitely going to want Acrobatics, Perception, Stealth, Intimidate, Diplomacy, Knowledge (Local), Disable Device, and Drive. If cars aren't available in your game world, though, then replace Drive with something like Sense Motive or Survival.
Then there are feats. John is, primarily, a combat character on a mission of vengeance. While a human with at least four levels of fighter is a good start, it's still a good idea to spend your feat slots carefully. The following feats are grouped together, and they are merely suggestions. If you find more effective ways to represent John's fighting style (or you find yourself in a world with no more guns, and no more bullets), then you might need to make adjustments.
The first feat you're going to want to take is Vengeance. This story feat provides John with bonuses to saving throws, attack rolls, and weapon damage rolls against his sworn enemy, and all people who work for them. It only works for the story we saw play out in the films, though, so this might be one to jettison if you don't have a specific foe that's going to last for several arcs to give you some real bang for your slot.
Moving on to shooting feats. You're going to start with Point Blank Shot and Precise Shot. These are your bread and butter, since you're going to be doing a lot of firing. Weapon Focus with handguns, then Weapon Specialization with the same, should also be on the list. This gives you access to Point Blank Master, which lets you keep shooting in melee without drawing attacks of opportunity. Rapid Shot is good to have, assuming you're using modern firearms, otherwise you'll need to invest in Rapid Reload, and possibly some magic items, in order to fire your full measure of attacks every round.
Catch Off-Guard would allow you to recreate the story of how John once killed three men in a bar (and two men in an airport) with a pencil. Accomplished Sneak Attacker will up your sneak attack damage, and help you deal with the loss caused by multiclassing.
In order to deal more damage, it pays to have at least one or two feats on your list that you can pop to really hurt your enemies. Deadly Aim is ideal for making your shots do more damage, on top of any sneak attack you're dealing. Power Attack is good for builds where you have high enough Strength, but you can also take Weapon Finesse and Piranha Strike if you want to make full use of your Dexterity score. If you're feeling the crush of not having enough resources, you could be excused for not focusing on melee, and counting on your sneak attack to hold up that part of combat.
Other feats you may find useful include Snap Shot, Improved Snap Shot, and Combat Reflexes. This lets you shoot as an attack of opportunity, and to threaten squares around you, which gives John all sorts of tactical advantages when his foes try to close with him and get blasted for their trouble.
Lastly, you can invest in Improved Unarmed Strike if you want to, but practically speaking there are better uses for your feat slot. Brass knuckles, a spiked gauntlet, or a cestus are a mechanically better option, even if they aren't part of the source material. Alternatively, dipping 1 level into Brawler would be useful, making your mix-ins 4 levels of Trench Fighter, 1 level of Brawler, and the rest all Rogue.
Gear and Story
It's not enough to be one of the world's greatest assassins... you need to back up the talk. One of the ways you do that is making sure you bring the right gear to the fight.
Sniper Goggles are going to be extremely helpful here. While they might not jive with John's typical look, he also tends to be within 30 feet when he starts a firefight. In the one scene where he makes a long-range shot, though, he does so with a scope. His guns are certainly masterwork quality, and the same is true of his blades. Oil of Silence is a great way to have a shootout in a club without everyone immediately realizing bullets are flying, letting you maintain your stealthy approach without giving up your favored weapons. The Gunman's Duster is an ideal source of armor, and it would allow John to get out of the way of a lot of bullets. Beyond these simple tools, John rarely needs more than his determination to keep going, and his unwillingness to give up until the job is done.
Lastly, you need to know who your John Wick is. Are you a master assassin who left the shadows behind, drawn back in against your will? Are you, instead, the Ghost who delivers death, then vanishes without a trace? Are you a mercenary? A loyal servant? Or are you still looking for your way out of the life so you can be something other than a cold-blooded killer? The choice is up to you, but you should have an idea of where you're going before you start playing.