Johannes von Mainz was a Prussian Shadowhunter and farmer.
In 1832, Johannes called the entire Clave to his farm in Prussia, claiming to have summoned an angel to his cow barn. However, the angel turned out to be his son Hans covered in gold leaf and wearing a wooden frame pasted with feathers. Johannes was humiliated and became ultimately responsible for the Clave's cautious attitude towards claims of angel sightings.
- The Shadowhunter's Codex (mentioned only)