Born some time between 2245 and 2247 (as evidenced by Dennis Crocker), The King was a member of one of the original tribes of New Vegas before they were united and brought to power by Mr. House. He and his gang took up residence in an old Elvis impersonation school. They believed it to be a place of worship due to the posters and holotapes all of one man, whose real name couldn't be found, but was only known as "The King." In the upper levels of the school they found outfits that the original king would wear and vast amounts of hair gel. The King watched the old holotapes of the man, learned to speak like him, and started to teach others to do so. Unlike other gangs in the Mojave Wasteland, the Kings are built on respect and don't go looking for their next fight. His right hand man is Pacer, a childhood friend who sometimes tends to undermine his peaceful intentions. He has a cyberdog named Rex, which the player can obtain as a companion.
Killing Pacer, the King's close friend, results in only one option of dialogue for the courier: "I was hoping to get some work.." and only one answer from the King: "I had some.. But my close friend was whacked...". After that players can't get any quests but can get Rex as a companion. (To get to King's quests type in the console: prid 0010e0ce, moveto player click Pacer's body with console opened resurrect.)
The King can be found either in the theater, or in his room on the 3rd floor.
Sleeping in the King's bed grants the Well Rested bonus, despite not being an owned bed.
Killing The King results in Mr. New Vegas attributing your actions to the NCR, and you will hear NCR troopers commenting on defeating a gang in Freeside.
The King is one of the characters that the player must eat in order to earn the Meat of Champions perk.
The King's favor can be used to complete the Kings' Gambit quest almost instantly.
The King is the only character, besides Old Ben and Santiago, with a permanent smile, even in combat.
The King is quoted by Mr. New Vegas as calling NCR refugees "the devil in disguise" and that he doesn't want to see NCR "in the ghetto," and calling for a mass "return to sender," all of which are songs by Elvis Presley.
Upon resolving the conflict with the NCR, The King mentions that he would like to see "A little more talkin' and a little less fightin'." This is an Elvis reference to the famous line "A little less conversation, a little more action."
In addition, a brief voice clip of the King on Radio New Vegas can be heard if the Courier convinces the King to side with the NCR after the conclusion of G.I. Blues. The voice clip is as follows: "I feel so bad, I think it's time we reconsidered, baby." Both "I Feel So Bad" and "Reconsider Baby" are songs by Elvis Presley.
If you talk to the King after G.I. Blues he'll say that things have been better since you helped out with those "soldier boys." A reference to the Elvis song, "Soldier Boy."
His outfit itself is also reference to another of Elvis' songs, "Viva Las Vegas," as is the picture of him on the Collector's Edition playing cards similar to the promotional picture for the film with the same name, also starring Elvis Presley.
At the end of G.I. Blues, when talking to the King, he says "Thank you, thank you very much" in response to helping Pacer with the NCR. This is an obvious reference to Elvis Presley.
When The King introduces Rex to the Courier, he says that he is "All shook up" about Rex's condition. "All Shook Up" is yet another Elvis song.
During the development process of the game's story, there was going to be a quest that the Courier, if male, would wake up drunk next to Rose of Sharon Cassidy and both get married in an ending, with the King singing an Elvis song.
ps3 If you speak to The King about joining the King's Gang before the completion of his quest Nothin' But a Hound Dog, he might decline. Returning later after completing it, the option will not be reopened, (unless The King owes you a favor which is earned in another mission) and it will be thereafter impossible to join the King's Gang. It is uncertain if this is a bug or intentional. [verified]
ps3 If the King is dead and you have a good Reputation with Freeside, you will still get various items from the Kings and they won't be hostile towards you. [verification overdue]