1054, the Great Schism, in which the Western (Roman Catholic) and Eastern Orthodox churches separated from each other. After a number of earlier such schisms, the breach was later repaired, but this one continues nearly 1000 years later.
... power for any period of time without a legitimate basis of authority.
The first to have the title of "Tyrant" was Pisistratus in 560 BC.
In modern times Tyrant has ...