- 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
Served aboard the U.S.S. Enterprise NCC-1701 in 2267. O'Neil investigated a missing starship crew on Beta III and was captured and absorbed. Later he betrayed his shipmates to Landru's lawgivers.