The Apostle Paul wrote the most books in the Bible - traditionally 13-14 books (Romans, 1-2 Corinthians, Galatians, Ephesians, Philippians, Colossians, 1-2 Thessalonians, 1-2 Timothy, Titus, Philemon, and possibly Hebrews). John wrote 5 books (Gospel, 3 Epistles, Revelation), Peter wrote 2 Epistles, and Luke wrote the Gospel of Luke and Acts (2 books).