Pirate King is a title claimed by the king of the pirates. The Pirate King has historically been an idiot, a woman, and British, all of which do not make a very good King - at all. The Pirate King's power mostly derives from his or her ability to be a pirate, which is quite easy.
Historically, the ten (or eleven, it is undecided) Pirate Rulerz would meet in a secret location to discuss the election of the Pirate King. Usually, this was done by the Rulerz engaging in an extremely violent, long-lasting battle between the Rulerz' forces at the secret location. Casualties would usually number in the thousands, along with many civilians and lesbians who were killed for the hell of it.
Once the fighting had been reduced to two contendors, all remaining forces of the dead Pirate Rulerz would join either side. This was known as the "cockus". The two sides would fight it out in a small square building in which the walls and ceiling were covered in spikes. The regulator of the fight would be the incumbent Pirate King. Once the battle was finished, whoever remained alive would claim the title of Pirate King. Also, something about the great and mysterious treasure of One Piece, but nobody really cares about that.
However, if both Pirate Rulerz died in the battle, then the battle would continue until one person survived, and that would become the new Pirate King. However, if two people survived and did not want to fight, they were declared pussies and slaughtered by the incumbent Pirate King, who would continue to rule (but over what?).
After the voting ceremonies had taken place, the new Pirate King would emerge victorious from the slaughter. By this point, most of the pirates in the world would be dead, and so it was the new Pirate King's job to announce his plans to the remaining pirates. This was the inauguration ceremony, after which the incumbent Pirate King would kill himself. This was known as the "Dread Bloodlet".
The Pirate King's mission afterwards was to assemble entire armies of pirates to lead in his conquests. He would do this by traveling from town to town and stealing booty, which would (somehow) urge others to follow his ways and join him. Eventually, according to tradition, the Pirate King would amass so many followers that they would form themselves into various factions. The rulers of these factions would become the new Pirate Rulerz. Once ten (or eleven) pirate rulerz were assembled, the Pirate King would announce the new location of the next voting ceremony and the process would repeat itself.
The Pirate King "voting ceremony" was actually only held once, and the winner was a pirate named Monkey D. Luffy. However, Jack Sparrow claimed the title because he had been a better pirate and Luffy was too young at the time. Sparrow did a greate job at assembling everybody, and at the next voting ceremony, a woman was elected. At this point, ten out of eleven of the Pirate Rulerz decided that a pussy could not rule over the pirates, and they re-elected Luffy.
Another historical problem with the ceremonies was that no Pirate Rulerz actually wanted to take place in them because of the violence that the ceremonies entailed. Also, the title's survival depended on the constant denial of the pirates by the local authorities. Eventually, the government understood that this was going on and sent an entire army to put a stop to it.
And they did. The pirates were dispersed all over the world, and nobody cared anymore about being a Pirate King, though many would continue to claim the title, if only to have a powerhouse to defend the pirates against the vile villians known as "Snail Sucking Grandma Seducing Frog Eating Bastards", who are known as the French to common citizens. Ninjas come in the picture too, but at second rate when the French are involved. Oh le poo poo.
- Gold D. Roger: Undefeated in battle, crippled by polio.
- Jack Sparrow: Famous for being King for a month. Potential candidate as the next Pirate King.
- Teague Sparrow: Historic Pirate King. Also Jack's father. (1895-1990)
- Guybrush Threepwood: Famous for his iconic battle cry. ("How appropiate, you fight like a dairy product!") Murdered during a ninja raid lead by Shinobi Lord Ryu Hayabusa. (1990-1993)
- Elizabeth Swan: The only Pirate "Queen" as yet. (1993-2004)
- Monkey D. Luffy: The recently elected Pirate King. (2005-Present)