- 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
Military officer with the United States Army Air Corps on 20th-century Earth. Denning, a veteran of two world wars, was deeply concerned for his nation's security, and about the potential risk that extraterrestrials might pose.
General Denning investigated the crash of an extraterrestrial spacecraft near Roswell, New Mexico, on Earth in 1947. Denning's investigation was conducted under the direct orders of American President Harry S Truman. He found himself face-to-face with three Ferengi who had inadvertently travelled back in time from the 24th century, fielding their proposition to engage in trade. The apparent leader of those extraterrestrials, Quark, offered to sell the general's nation-state advanced technology for millions of bars of gold, but he also warned that he would be willing to do business with the Russians if the Americans wouldn't play ball. Denning was particularly concerned about their weapons technology. After being mistreated by the military investigators, the Ferengi eventually got away in their ship, and Denning was willing to let the existing cover story lay that the crashed "flying saucer" was just a weather balloon.
General Denning had a brother-in-law who was a car salesman whom he didn't trust; Quark reminded him of that relative. Even though he was beholden to President Truman, Denning had a low opinion of his commander-in-chief, calling him a "little piano-playing Democrat" — even though he acknowledged that that Democrat wasn't as dumb as he looked.