Chuck is a major contender, imo, along with Jerry Lee Lewis (surely the "King" of Rock 'n Roll piano), and Elvis. Elvis was more the "jester" that brought it to the limelight, imo ... but I admit, I'm biased cuz I've always diskliked how frontmen/showmen always tend to get the attention over cornerstone musicians. If it weren't for the musicians (particularly the songwriting ones), the frontmen would have little upon which to base their act. Good lyrics are essential, but so is a good song. All in all it's a balance of lyrical impact (not to be confused with substance), catchy tunes and stylish musicianship, and a great show. If you can add a virtuoso musician or two, then you really have a winner.

But really, the bottom line is: it's mostly a matter of luck. You can have all these things and still fail. So much depends on having the right business connections at the right time, the knack and the endurance to harness them, and capturing and maintaining the faith of an oh-so fickle and diverse audience.

In regard to "kingship," I think it would be an oversight not to recognize the gigantic influence of all the fantastic Blues players, who were essentially rockin' long before the term "rock 'n roll" was ever coined.