noun
A person who represents a group, organization, or country in an official capacity.
彼は会社の代表者として会議に出席した。
He attended the meeting as a representative of the company.
各国の代表者が条約に署名した
Representatives from each country signed the treaty.
代理人 is a legal or formal proxy acting on behalf of someone, often with legal authority, whereas 代表者 is a more general representative of a group.
Compound of 代表 (representation) + 者 (person). The reading is on'yomi.