Watch some Star Trek dude
I think control over the masses throughout space will be largely dependent upon our ability to transfer information. Right now there are lots of hurdles to get over... communicating to the other side of the world creates a time delay and speaking with astronauts is a tedious task.
If information is not readily shared and transferred across space, societies will be more reliant on managing and ruling over whatever area they are capable of reaching immediately.
There is no use for a ruler over a quadrant or sector of space if that ruler cannot influence the people which inhabit that area.
Assuming we survive long enough to span the universe, it may be more common to see small settlements with independent governing systems as opposed to an emperor of some sort. But who knows, with technology we may find ourselves quite easily enslaved by a singular government. Only time will tell.