Sirens are scrapped enemies, the only thing that proves their existence is a concept art showed during the Making of Video.
- Even though Sirens were scrapped from the game, their concept art can be found in many places in Battle Out of Hell:
- In Orphanage, on many paintings.
- In Loony Park, on the main entrance sing and exterior walls of Acid Bath.
- In Lab, in the room on top of the Tank.