- Star Trek: The Motion Picture
- Star Trek II: The Wrath of Khan
- Star Trek III: The Search for Spock
- Star Trek IV: The Voyage Home
- Star Trek V: The Final Frontier
- Star Trek VI: The Undiscovered Country
- Star Trek Generations
The nullifier core is the main engineering element of the propulsion systems on Romulan Warbird's. The nullifier core must be kept within strict levels of performance in order to prevent a phenomena known as magnetic disruptions, that can be detected by other ships while the Romulan Warbird is cloaked.