Simony is the ecclesiastical crime and personal sin of paying for offices or positions in the hierarchy of a church, named after Simon Magus, who appears in the Acts of the Apostles 8:18-24. Simon Magus offers the disciples of Christ payment for the power to perform miracles.

The intertwining of temporal with spiritual authority in the Middle Ages caused endless problems with simony and accusations of simony. Secular rulers wanted to employ the educated and centrally organized clergy in their administrations, and often treated their spiritual positions as adjuncts to the secular administrative roles.