noun
Refers to a person or entity that rules, governs, or controls a country, organization, or group. Can be used in political, historical, or metaphorical contexts.
その国の支配者は国民の声に耳を傾けなかった。
The ruler of that country did not listen to the voice of the people.
彼は会社の絶対的な支配
He acted as the absolute ruler of the company.
指導者 means 'leader' in the sense of guiding or directing people, often with a positive or inspirational nuance, whereas 支配者 can carry a more authoritarian tone.
Compound of 支配 (しはい, 'rule, control') and 者 (しゃ, 'person'). The word 支配 itself is a Sino-Japanese term from Middle Chinese elements meaning 'support' and 'control'.