It's popularly assumed that the Roman soldier who pierced Jesus' side to confirm his death had his blindness cured when he touched his eyes with his blood-stained hands. This actually isn't anywhere in the Bible, but comes from a medieval bast-seller The Golden Legend. And who would hire a blind soldier anyway?
The bit about Mary Magdalene being a harlot. She was actually a former victim of demon possession, while the harlot was from another passage. Also the bit about her being in love with Jesus, which might qualify as one of the oldest examples of Shipping by the fandom.
Many other notions that have become canon in modern Biblical religions (both Christianity and Judaism) actually never appeared in the Bible, or require an extremely strained reading of Scripture to arrive at. Purgatory appears to be a Catholic invention, the pre-tribulation Rapture was invented (or at least popularized) by John Darby in the 19th century, etc..
Name's the Same: The Catholic and Orthodox Bibles have four different Judases. One is a heroic freedom fighter, the other is an apostle and another appostlebetrays Jesus. There was another Judas who lives in Damascus.