- 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
One of the Species 8472 individuals being trained to impersonate Starfleet personnel. O'Halloran had difficulty maintaining his human form, reverting to his natural state three times in one week.