How Star Trek Pulled Off Two Kirks Interacting In The Enemy Within

In the "Star Trek" episode "The Enemy Within" (October 6, 1966), Captain Kirk (William Shatner) beams up from the planet Alpha 177 covered in a mysterious magnetic dust. Unbeknownst to any of the Enterprise crew, the dust has fouled up the transporter and created a second Kirk inside its memory buffer. After Kirk leaves the room, the second Kirk materializes ... but displays an altered personality. It seems that Kirk has been bifurcated into a gentle version of himself and a cruel, aggressive version of himself. For much of "The Enemy Within," the Evil Kirk stalks around the halls of the U.S.S. Enterprise, startling the crew and accosting Yeoman Rand (Grace Lee Whitney). Gentle Kirk soon realizes that he needs his aggression back in order to be whole. Eventually, the two Kirks confront one another. 

"Star Trek" had a modest budget back in the day, and it certainly didn't have the resources to employ split-screen photography to depict Shatner standing next to himself. Instead, the episode used clever editing and body doubles to make it look like two Kirks were on the bridge. Evil Kirk was also given dark eye makeup and eerie lighting, and the writers added a scratch to Evil Kirk's face, ensuring audiences could tell the difference. 

In the book "Captains' Logs: The Unauthorized Complete Trek Voyages," edited by Mark A. Altman and Edward Gross, producer John D.F. Black recalled shooting "The Enemy Within," an episode he described as "one of the easy ones." It seems show creator Gene Roddenberry, who frequently objected to certain "Trek" stories was okay with this one. 

The difficulty came in shooting two Kirks at once. The choreography was a headache.

It's well-known by Trekkies that Gene Roddenberry was frustrated by the traditional stories that "Trek" writers wanted to tell. "The Enemy Within" was written by sci-fi legend Richard Matheson, and it seems that the author and the creator, in a rare case of synergy, were instantly on the same page. Black recalled a meeting Matheson had with Roddenberry — one he rushed in on at the last minute — and that he was shocked to find the vibe so copacetic. He said: 

"[Matheson] understood what the show was. He did not think it was a disguised comedy, he did not think it was 'the last man on the moon.' He knew what we were doing. He tuned in immediately, as he had done on 'Twilight Zone' before, so it was difficult for [Roddenberry] to make any kind of real arguments about structure. He had some b****es about where the story turned here and where it turned there, but by and large that was one of the easy ones."

Matheson, by coincidence, also authored the "Twilight Zone" episode "Nightmare at 20,000 Feet," which also starred William Shatner. 

It was "Enemy Within" director Leo Penn who confessed to blocking difficulties when shooting the episode. "Captain's Logs" quotes an interview Penn once gave with Starlog Magazine: 

"It was a challenging show to do. We had to hire a photo double, and it was particularly tough in the scenes where [both Kirks] had physical contact. You had to resort to shooting over the double's shoulder, switching them around and so on. It took time, but the results were worth it."

Everything looked fine, although the photo double's hair didn't quite match Shatner's.

Indeed, in the photo above, one can see that the photo double seemed to be taller than Shatner, and had larger hands and broader shoulders. In quickly edited fight scenes, such differences wouldn't be noticed, but in a wide shot, they're pretty obvious.

The photo double was an actor named Don Eitner, who had previously played a helmsman in the "Star Trek" episode "Charlie X" (September 15, 1966). Eitner was a reliable character actor whose credits number in the hundreds. Prior to "Star Trek," Eitner had already played soldiers, cops, and various supporting characters in TV shows like "West Point" and "Death Valley Days," and in fun B-movies like "Beginning of the End" and "Kronos." Eitner later showed up in single episodes of "Lost in Space," "The Green Hornet," "The Virginian," "The Fugitive," "Mission: Impossible," "That Girl," and "Lassie." His TV career lasted into the mid-1980s when Eitner seemingly retired. Name a hit show from that era, and Eitner was probably on it.

Eitner passed in 2018 at the age of 83. He may not have been a major celebrity, but Hollywood could not function without reliable supporting players like him. Because he stood in for William Shatner, Eitner can also boast that he was one of the few actors to have played Captain Kirk on camera. He also got to punch, be punched by, and hug Shatner, another claim very few actors can make. 

As director Penn said, it was all worth it.