authoritarian

Short definition from Wiktionary

Adjective

1. 1
   Of, or relating to, or exhibiting strict obedience to an authority; favoring authoritarianism over civic and individual liberties.
2. 2
   Demanding obedience to authority; marked by authoritarianism; dictatorial, tyrannical.
3. 3
   Tending to impose one's demands upon others as if one were an authority.

Noun

1. 1
   One who commands absolute obedience to his or her authority.
2. 2
   One who follows and is excessively obedient to authority.