All excerpts from Wikipedia's entry for "Cult of Personality." All emphasis mine.
A cult of personality or personality cult arises when a country's leader uses mass media to create a heroic public image through unquestioning flattery and praise. Cults of personality are often found in dictatorships.
Generally, personality cults are most common in regimes with totalitarian systems of government, that seek to radically alter or transform society according to (supposedly) revolutionary new ideas. Often, a single leader becomes associated with this revolutionary transformation, and comes to be treated as a benevolent "guide" for the nation, without whom the transformation to a better future cannot occur. This has been generally the justification for personality cults that arose in totalitarian societies of the 20th century, such as those of Joseph Stalin and Adolf Hitler.