Dictatorship is a negative term for autocracy or oligarchy. The term derives from the Roman Republic, where in emergencies an individual could be given absolute powers for a limited term. The Roman Republic viewed autocracy negatively and the position of dictator suspiciously, especially after several military generals used the position during civil wars, and the later Roman Emperors avoided using the title, despite being autocrats.
More recently, the term is almost always used negatively, with the exception of Communists, who explicitly advocate a "dictatorship of the proletariat". Despite this, leftist Wikipedia almost exclusively focuses on "right-wing" dictators in their "Dictatorship" article and and have no pictures of Communist dictators.