Commodus, The Worst Emperor of Rome
Commodus was a very very arrogant sort of child. He was the child of Marcus Aurelius, the last of the 5 "good" emperors of Rome. All Commodus wanted to do was play and have fun! Why be obsessed with stamping out barbarian tribes that mean no threat to Rome? Unfortunately for him, that's the exact kind of thing that his father, Marcus Aurelius, was obsessed with. Marcus Aurelius died fighting in the war.
After Commodus was given the throne, he began to collect the most exotic animals he could find. He planned to battle them in the Roman Colosseum. Commodus did this daily. You might think that this wouldn't exactly classify as being a bad emperor. But, Commodus did not take part in any government activities. Some say that he closed down all the temples to the gods.
For this, the gods cursed Commodus with madness. Every time he ran out of animals to kill, he killed the senators. As the Roman government fell weaker and weaker, more and more attempts to assassinate Commodus were made. One attempt was to poison his beer but Commodus was strong. He resisted the poison and survived. Eventually, he was drowned by his own personal trainer, Narcissus. Now, let's not get confused with the Narcissus who got turned into a dandelion cuz he was so beautiful and almost died staring at his reflection. This is a completely different Narcissus. Some say the Narcissus was possessed by the god Apollo when Commodus was drowned.
Sadly for Rome, this was only the beginning for it's decline.