A person who contributes to a project, cause, or field; neutral modern term.
He is a contributor to the open-source project.
tributary person
Historical term for a person who pays tribute to a ruler or state; rare in modern usage.
In ancient China, tributary persons from neighboring countries offered tribute to the emperor.
Compound of 貢献 (contribution) + 者 (person). The historical sense derives from the older meaning of 貢献 as 'tribute'.