WordNet sense 1 (a person who behaves in an tyrannical manner):

dictator

WordNet sense 2 (likened to a dictator in severity):

dictatorial

WordNet sense 3 (not inclined to grant permission; severe in discipline):

unpermissive

WordNet sense 4 (expecting unquestioning obedience):

overbearing

WordNet sense 5 (tending to domineer):

domineering

WordNet sense 6 (characteristic of an absolute ruler or absolute rule; having absolute sovereignty):

autocratic, despotic, tyrannical

WordNet sense 7 (not in agreement with or according to democratic doctrine or practice or ideals):

undemocratic