noun
supreme leader; ultimate leader
Refers to the highest-ranking leader of a country, organization, or movement, often with an authoritarian or absolute connotation.
その国の最高指導者は絶大な権力を持っている。
The supreme leader of that country holds immense power.
指導者 means 'leader' in a general sense, while 最高指導者 specifically denotes the topmost leader, often with an authoritarian nuance.
Compound of 最高 (さいこう, 'highest') and 指導者 (しどうしゃ, 'leader').