John Henry "Doc" Holliday is one of the most famous names from the era of the Wild West. A Southern gentleman of means and education, Doc was struck by one tragedy after another. When he could no longer practice his trade due to his tuberculosis, he had to turn to another one to make his way in the world. That's how he became a gambler, using his sharp intellect to come out ahead. Of course, his hot temper got him in trouble, and he often shot his way out of it. A friend to the famous Earps, Doc was both a great strength, and a great weakness for them.
If that's the kind of character you'd like to have in your party, this guide should get you started. Also, if you're looking for more Badasses of History, as well as the cast of Game of Thrones, and heroes from both Marvel and DC comics, the Character Conversions page at Improved Initiative has more guides for you to peruse.
Race, Attributes, and Traits
Much has been written about the infamous Doc Holliday, and while not all the accounts agree, there are a lot of consistent facts. For example, we know that Doc was born in 1851, in Griffin, Georgia. His father, Henry Holliday, was an important man in their town. A pharmacist by trade, his father was involved in local politics, as well as a member of the Freemasons. Doc's mother died of tuberculosis when he was 15, and as a coping mechanism he threw himself into his studies. He attended college in Philadelphia, and became a dentist who was fluent in many languages. Including Latin. Unfortunately for Doc, though, he contracted consumption himself.
Looking at this snapshot of his life, we see a man of intelligence, wisdom, and dexterity. Doc was never made to do hard labor, and though he was cultured and gentlemanly, he was often described as belligerent and hot-tempered. So, in this instance, we are looking at a human with high dexterity and wisdom, a good intelligence, and whose other stats are up to the player.
When it comes to traits, it's important to choose options that describe the character's history, and which you'll use fairly often. Reactionary (+2 trait bonus on Initiative checks) is particularly useful for a gun hand who's going to be getting involved in the occasional duel. Chip on The Shoulder (whenever a creature fails an Intimidate check against you, you gain a +2 bonus on your next Intimidate check against that creature), or Civilized (gain a +1 trait bonus on Knowledge (nobility) and Knowledge (local) checks) would fit Doc quite well, also. And, if you are looking for something that duplicates his lifestyle, you might want to try the Hedonistic drawback (if a day goes by without a reward of at least 10 gold pieces, or 1 hour of entertainment, you must make a DC 20 Fortitude check. Failure means you start the day Fatigued, and the condition remains for 4 hours, or until you're either rewarded or entertained).
Class and Skills
While he was a dangerous man with a gun, as well as with the long, bladed knife he carried, Doc was also famed as a gambler. In addition to playing cards for money, he was also a dealer for both Poker and Faro. The best way to represent this unusual cadre of skills is to start Doc off with the Maverick archetype of the gunslinger. Mavericks lose out on Gunslinger's Dodge, Pistol Whip, and Gunslinger's Initiative, but instead they gain Stacked Deck (allowing them to gain bonuses on Bluff, Profession (Gambler), and Sleight of Hand checks), Fist Fighter (treated as having Improved Unarmed Strike as long as they have 1 grit point left), and Gun Twirl (gaining the Dazzling Display feat, and being able to use it with any firearms even without having Weapon Focus as long as he still has 1 grit point left).
For players who want to add a dash of flavor into the pot, a few levels of rogue can spice up your Holliday. Rogue Tricks like Resiliency, which give you temporary hit points if you're brought below 0, show how tough he was to kill, despite being a gentleman with a debilitating disease. Sneak attack is always good to have, along with Uncanny Dodge. If you wanted to focus on his backup weapon, you could even take the Knife Master archetype.
Regarding Doc's skills, he had quite a number of them. Bluff, Sense Motive, Perception, Sleight of Hand, Linguistics, and Profession (Gambler) are no-brainers. If you still have points left, then you might find Intimidate, Knowledge (Local), and Knowledge (Nobility) useful. Disguise isn't out of the question either, as Doc went on the run from the law several times, and assumed false names and appearances while he was doing so.
Which feats you give Doc are going to depend largely on how you intend on playing him. Do you want him to focus on dealing more damage to individual targets (the way he would as a duelist), or would you prefer to make him a rapid-fire gunslinger? The sort that would turn the OK Corral into a hail of lead, and a fog of gun smoke?
The basic feats you're going to want to invest in will be Point Blank Shot, and Precise Shot. Since your primary weapon is likely to be your guns, you should also take Deadly Aim. If you want to make sure you're not caught off-guard, and you have the slots, you may want to take Improved Initiative and Quick Draw as well.
If you're going the one-on-one route, you want to make sure every shot packs the biggest punch possible. In which case, you may want to look at the Vital Strike feats, along with their accessories like Devastating Strike to give you a little extra punch. When you combine those with a high Initiative, and even a few sneak attack dice, getting off that first shot can be truly explosive.
Alternatively, if you want to fill the air with as much lead as possible, you're going to want to focus on the Two-Weapon Fighting feats. Those feats, along with Rapid Shot, and Clustered Shots, can punch holes in any line of defense. It's important to take a look at your weapons, though, and to make sure you can reload as a free action often enough to get every shot you need for the round. While the full-auto option can put a lot of lead in the air (and do serious damage once you start adding your Dexterity modifier to your damage, on top of the bonus damage from Deadly Aim), it tends to eat through your resources in short order. So you'd better hope you have enough time to put twelve new rounds into your guns, otherwise you're going to have a very angry dragon wondering who just used it for target practice.
Also, if you decide to go the rogue dip option, you can boost your sneak attack with the feat Accomplished Sneak Attacker, adding 1d6 up to half your character level. Assuming, of course, you're going to get into a lot of situations where you shoot first.
Tools of The Trade
Gear and Story
Doc was known for several things in his life. One was that he was always nattily dressed, holding to the standards of both wealth, and high society he'd been brought up with back East. Doc always packed two guns, one in a shoulder holster and one on his hip, as well as a particularly keen knife. While these weapons weren't enchanted historically, if you want to keep up with the enemy's challenge rating, it might pay to invest in some choice magic. Particularly if you can get a Dueling weapon, since that gives you a +4 to your Initiative checks.
As to Doc's story, well, that's up to you. Is your Doc an indigent gambler with a talent for piano playing and card dealing, in addition to a fast draw and a bad cough? Is he helping his friends fight a feud, or are his intentions more noble? Is he a disagreeable lush prone to pulling steel or skinning a gun, or does he try other means of settling disputes until there is no other option but a spirited exchange of lead? Those are your questions to answer.