Formal:
* Envoy: This is the most common synonym and is often used in diplomatic contexts.
* Diplomat: This word emphasizes the individual's role in conducting diplomacy.
* Minister Plenipotentiary: This is a formal title for a diplomatic representative with full authority.
* Consul General: This term refers to a diplomatic official representing their country in a specific region or city.
Informal:
* Representative: This is a more general term that can be used for anyone representing a group or organization.
* Messenger: This word emphasizes the role of conveying messages or information.
* Spokesperson: This term suggests someone who speaks on behalf of a group or organization.
Figurative:
* Herald: This word implies someone who announces or brings news.
* Emissary: This word suggests someone sent on a special mission.
The best word to use will depend on the specific situation and the tone you want to convey.