WordNet sense 1 (offensively self-assured or given to exercising usually unwarranted power):

autocratic, bossy, peremptory, dominating, high-and-mighty

WordNet sense 2 (tending to domineer):

domineering

WordNet sense 3 (used of a person's appearance or behavior; befitting an eminent person):

distinguished, grand, imposing

WordNet sense 4 (having or expressing dignity; especially formality or stateliness in bearing or appearance):

dignified