Who wrote the shortest book in the Bible?

The shortest book of the bible (including books of the New Testament) with fewest words 3 John --- 1 chapter, 14 verses with 299 words, and 2 John --- 1 chapter, 13 verses, 303 words with the fewest verses. The author of those 2 books is the apostle John.

The smallest book of the Old Testament is Obadiah (1 chapter, 21 verses, 670 words) which presumable was written by the prophet Obadiah.