Learn more about Self-proclaimed monarchy
A self-proclaimed monarchy is a monarchy that is proclaimed into existence, often by a single individual, rather than occurring as part of a longstanding tradition. It is thus at least initially the opposite of most hereditary monarchies, although if a self-proclaimed monarchy is successful, it will evolve into a hereditary one.
Throughout history there has rarely been a political office higher in stature and power than that of king or emperor. In republican dictatorships these titles have often proven too tempting to resist, and often at the apex of his power, a dictator will sometimes decide to proclaim himself king, and thus turn the nation into a monarchy.
In 1804 French dictator Napoleon Bonaparte decided to consolidate his power by proclaiming himself Emperor Napoleon I. Though this imperial regime would end with his fall from power, years later Napoleon's nephew Charles-Louis-Napoléon Bonaparte would be elected President of France and proceed to declare himself Emperor, as well.
In Haiti there were three such cases: Governor-General Jean-Jacques Dessalines became Emperor Jacques I (1804-06), President Henry Christophe became King Henri I (1811-20), and President Faustin Soulouque became Emperor Faustin I (1849-59).
A short-lived African empire was also created in 1976 when dictator Jean-Bédel Bokassa of the Central African Republic proclaimed himself "Emperor Bokassa I" and had a lavish coronation ceremony in 1977.
 In Fiction
In Star Wars Episode III: Revenge of the Sith, Chancellor Palpatine, after being revealed as a Sith Lord, announces to the Senate of the Galactic Republic that the Jedi have been plotting against him, and that the Republic will be reorganized into a Galactic Empire, with himself as emperor.