tyrannical
absolute, arbitrary, authoritarian, autocratic, coercive, cruel, despotic, dictatorial, domineering, high-handed, imperious, inhuman, magisterial, oppressive, overbearing, overweening, peremptory, severe, tyrannous, unjust, unreasonable
Antonyms
democratic, easy-going, lax, lenient, liberal, reasonable, tolerant, understanding