apocryphon · c. 4th century · Purported lost letter of the apostle Paul, mentioned in Colossians 4:16
A short Latin letter stitched together out of Pauline phrases, prompted by Paul's own reference in Colossians to a letter from Laodicea. It circulated in Latin bibles for a thousand years; Jerome knew it and rejected it. Kept and marked, because its presence in those bibles is a fact about the canon.