Julius Caesar was a warlord, a charismatic politician, and many believed that he was the greatest threat to ancient roman society.
Caesar served the republic of Rome for eight years in the Gallic Wars, where he fully conquered the region of Gaul.
The Roman Senate then demanded that Caesar disband his army and return to Rome as a civilian because Rome had not entirely agreed with what he had done.
He refused, and he crossed the rubicon with his army. This plunged Rome into a civil war (aka Caesar's Civil War) in 49 BC. After defeating the Roman forces, Caesar was appointed dictator perpetuo (dictator in perpetuity) in 44 BC.
Still, Caesar had to push three major issues, that eventually led to the Roman Senate murdering him.
Caesar was tasked with accepting a large honor from the Roman Senate. They wanted to present the honor to him formally, so they marched to Caesar's dwelling and approached him while he was seated. It was common political etiquette that Caesar stood up to greet the senators when they arrived, but he did not.
That was strike one.
There was another incident where Caesar attempted to undermine the Roman royal family by asking a crowd of political onlookers to chant his name instead of Rex's.
That was strike two.
The third and final attempt that Ceasar made to undermine the royal family was to encourage a crowd of people to support him in becoming king, despite the fact that it wasn't a democratic republic at the time.
For that, the Roman Senate singled Caesar out, and nearly 50 individuals stabbed him to death.