A person who oversees or manages an organization, operation, or group. Formal and somewhat bureaucratic.
He manages the whole project as its supervisor.
監督者 focuses on directing or overseeing work, like a foreman or director, whereas 統轄者 implies broader, higher-level control.
Compound of 統轄 (とうかつ, 'unified control') + 者 (しゃ, 'person'). The exact historical derivation is uncertain, but the kanji components reflect the meaning of a person who exercises comprehensive oversight.