A popular belief stemming from the Greco-Roman historian and statesman Cassius Dio is that the rise of Commodus, the son of Marcus Aurelius, to the emperorship of Rome in 180 AD coincided with the beginning of the end for the Western Roman Empire. Calamitous events would follow for the next three centuries, but as far as Cassius Dio was concerned, Commodus was the first guy stripping floorboard on the renovation.
Setting the tone for subsequent leaders of a similar ilk, Commodus got very into the idea of himself-as-the-kingdom, a personality cultist whose proto-fascism set the stage for his own assassination in 192. Any time you get the chance to be the marker of the end of a quasi-familial dynasty, well, I guess you have to take it.
On the non-hereditary side, reigns of power take all shapes and forms (though, if we’re being honest, if it isn’t in sports, it usually ends in assassination). Many franchises have experienced periods of stupendous success followed by tumultuous lows, but right now, the Golden State Warriors are undergoing the very worst downfall in recent memory.