Riddle of the Sphinx...

Let's see how much you realize,
In what I attempt to say,
The thing is really quite ironic,
and usually begins with J,

A special person has this job,
In which you'll always know,
A nice little scepter and a fancy hat,
Follows him wherever he goes,

So finally it comes to a head,
and this you'll never guess,
Who in the world does these things,
...and never goes away!