complainant; plaintiff; accuser
Legal term for a person who brings a complaint or accusation, especially in a formal or court setting. More specific than a general accuser.
The complainant submitted evidence to the court.
In this case, the identity of the accuser is protected.
告訴人 specifically refers to a person who files a criminal complaint with the police or prosecutor, whereas 告発者 can be broader, including whistleblowers or those reporting wrongdoing.
whistleblower; inside informant
Compound of 告発 (accusation, indictment) + 者 (person). The word follows a standard Sino-Japanese pattern for agent nouns.