There are some books of the Bible whose authors cannot be known completely.
The first five books of the Bible, - Genesis, Exodus, Leviticus, Numbers and Deuteronomy, are referred to in other parts of the Bible and by Jesus himself, as the books of Moses.
It is accepted that Joshua (or a scribe on his behalf) wrote the book of Joshua. Then various people wrote Judges,1 Samuel-2 Chronicles which appears to have been maintained as an official record. The authors of Ruth, Esther and Job are unknown. The Psalms were mostly written by king David, Solomon wrote Proverbs Ecclesiastes and Song of Solomon. The rest of the prophetical books were written by the people who gave their names to the books e.g Daniel, Ezekiel.
In the New Testament, Matthew, Mark, Luke and John were written by the men of those names; there are some variations on who people think wrote the Acts, but the most probably author seems to be Luke.
Paul wrote the following letters/epistles:
Romans, 1 & 2 Corinthians, Galatians, right through to include Philemon.
The author of the Letter to the Hebrews is not identified, but thought to also be from Paul. James, 1 & 2 Peter, 1,2,& 3 John and Jude were written by people of those names. The Revelation was written by John.