Tyrannicide or tyrannomachia is the killing or assassination of a tyrant or unjust ruler, purportedly for the common good, and usually by one of the tyrant's subjects. Tyrannicide was legally permitted and encouraged in Classical Greece. Often, the term "tyrant" was a justification for political murders by rivals, but in some exceptional cases students of Platonic philosophy risked their lives against tyrants. The killing of Clearchus of Heraclea in 353 BC by a cohort led by his own court philosopher is considered a sincere tyrannicide. A person who carries out a tyrannicide is also called a "tyrannicide".

John I was a scion of the French royal family who ruled the Burgundian State from 1404 until his assassination in 1419. He played a key role in French national affairs during the early 15th century, particularly in the struggles to rule the country for the mentally ill King Charles VI, his cousin, and the Hundred Years' War with England. A rash, ruthless and unscrupulous politician, John murdered the King's brother, the Duke of Orléans, in an attempt to gain control of the government, which led to the eruption of the Armagnac–Burgundian Civil War in France and in turn culminated in his own assassination in 1419.