- 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
Organisms that are from a domain that exists outside of normal space-time. Captain Archer was infected with these, preventing him from forming any new long-term memories. Twelve years later, T'Pol and Phlox figured out a way to eradicate the parasites, thereby eliminating them from the timeline altogether.