the writer; the author (often used for self-reference in articles or essays).
この記事の筆者は環境問題の専門家だ。
The author of this article is an expert on environmental issues.
筆者の意見としては、その計画に賛成できない。
As the writer's opinion, I cannot agree with that plan.
論文の末尾に筆者紹介を載せた。
I included an author bio at the end of the paper.