Classical scholars and historians of antiquity often assume that the concept of ‘monarchy’ (μοναρχία), like that of ‘tyranny’ (τυραννίς), was a part of Greek political terminology from a very early stage. Some eighty years ago, this theory was vigorously defended by Albert Debrunner, who argued that μοναρχία was the original Classical Greek constitutional term, functioning as a model for others such as ‘oligarchy’ (ὀλιγαρχία) and ‘democracy’ (δημοκρατία). In contrast, a lesser-known theory proposed by Gerhard Aalders asserts that the concept of people’s power, δημοκρατία, predates the emergence of μοναρχία and similar terms. This paper re-evaluates the origins of classical Greek constitutional terms by comparing these two alternative hypotheses, drawing on more recent scholarship, considering manuscript evidence, and discussing the historical context in which these Greek constitutional terms developed. Part I summarizes Debrunner’s theory and outlines the supporting arguments. Part II presents the main counterarguments, with a specific focus on the occurrences of μόναρχος (‘monarch’) in archaic Greek sources. Finally, Part III explores the implications of this critique and articulates four alternative hypotheses regarding the origins of μοναρχία and other classical Greek constitutional terms.