Demonize (verb)

1. To portray as evil or monstrous; to depict as a demon.
2. To speak against or denounce as evil.
3. To turn into a demon or make demonic.

Origin:

Back-formation from demonization, from demon + -ize.

Examples:

1. The media has demonized him and now the public sees him as a monster.
2. The religious leader demonized the new sect, calling them heretics.
3. The dark magic spell was used to demonize the innocent victim.
4. The politician has been demonized by his opponents for his controversial policies.
5. The writer demonized the corporation in his new novel, depicting them as ruthless and greedy.