- 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
An extremely frail, old-looking man living on the planet Arret in the antimatter universe discovered by the crew of the U.S.S. Enterprise on stardate 6770.3 (2270). Karl Four was actually the son of Karla Five, a woman who appeared to be several decades his junior. The backward flow of time in the antimatter universe accounted for this apparent paradox. Karl Four provided invaluable assistance in getting the Enterprise and her crew back home from the antimatter universe.