Final answer:
Caligula was the insane emperor who was murdered by his own bodyguards. He had a reputation for cruelty, megalomania, and enjoyed executing people for entertainment. He was eventually assassinated by a group of senators and guardsmen.
Step-by-step explanation:
The insane emperor who was murdered by his own bodyguards was Caligula. Caligula was known for his cruelty, megalomania, and extravagant displays of power. He believed in his own godhood, mistreated the senate, and enjoyed executing people for his entertainment. Eventually, a group of senators and guardsmen conspired to assassinate him.