Romans
There's an old Russian saying that the best government you could have is a good czar, and the worst government a bad czar. This is usually followed by a sad shake of the head, and an observation that there are damn few good czars.
Roman emperors also ranged from very good ones to very bad ones.
The Roman Empire is often used an as example of a decadent, tottering structure that crumbled easily, and failed in its attempt to hold power over a wide area of the world. The reality is a little more sobering. I just hope the United States lasts as long as the Roman Empire did.