Typically refers to the author of a specific book, article, or written work. More concrete than 作家, which implies a professional writer or novelist.
The author of this book is a famous historian.
著者インタビューを読むと、作品の背景がよくわかる。
Reading the author interview gives a good understanding of the work's background.
This is a valuable commentary by the author.
Please contact the author for further details.
著者 specifically means the author of a published book and sounds more official, while 書き手 can refer to anyone who writes, published or not.
corresponding author