score:12
The 40-author count is not unique to Jehovah's Witnesses, so I'll provide the names of the forty commonly-accepted authors. Note that the authorship of some books (Hebrews, for example) is debated, so the number and names vary slightly depending on which scholars you ask.
See When was the Bible written and who wrote it? for a matchup of names to books, along with approximate dates of authorship.