Lieutenant Leslie died in the opening moments of Obsession, attacked by a cloud creature which sucked all the red blood cells from his body. And then the character is seen on screen in a bunch of episodes that follow. Eddie Paskey, who played Leslie, told an interesting story about that on his now-defunct web site:

[Leslie] can be seen in nearly every episode from the first two seasons as well as a few from the third. He played many scenes as a “red shirt,” usually the first to die when exploring a planet. He is the only one though, to have died in one episode (“Obsession”) and returned in the next! This was due to the fact that a scene from the script that was never shot indicated that the victims were brought back to life! 

(Paskey’s site, eddiepaskey.com, has since fallen out of his control and is now registered in Pakistan. At time of writing, it contained 17 seemingly random posts. However, Paskey’s original site can be accessed through web.archive.org. He told the return-of-Leslie story here and here.)

The resurrection bit is a great story and it appears in many other places, including StarTrek.com, Memory Alpha and Wikipedia, but, as far as I can tell, it is not true.

Paskey was a regular on the Star Trek sets until health problems pushed him to quit the business, following Is There In Truth No Beauty? He was in 57 episodes, mostly as a background actor, and had a line or two in four episodes. His best bit was probably in This Side of Paradise: waiting outside the transporter room to beam down, Leslie refuses Kirk’s order to return to his station and replies to the captain’s “This is mutiny, mister” with “Yes sir, it is.” Paskey also served as Shatner’s lighting stand-in and body double and as the hand double for James Doohan when Scotty testified in Wolf in the Fold. 

Back to Obsession. I own the Revised Final Draft script from Oct. 4, 1967. It contains pages dated between Oct. 4 and Oct. 12. Shooting on the episode began Oct. 9.

In that script, there is no resurrection scene for any of the poor redshirts lost during the teaser. Two are killed outright and Rizzo lives for a while before succumbing. None is brought back. 

The director of the episode, Ralph Senensky, confirmed to StarTrek.com that no scene was shot in which a character came back. Senensky also addressed this phantom segment on his own web site. Instead of Leslie, he tells a story about Rizzo, who was played by Jerry Ayres. Ayres had earlier played O’Herlihy in Arena, another redshirt who died early on. About the reappearance of the actor in Obsession, Senensky wrote:

I have read an interview Jerry gave in which he said there was a scene filmed that explained that, but that scene ended up on the cutting room floor. I don’t think so; at least I didn’t direct that deleted scene, and…that scene was not in the script. 

Serensky seems to be mixing up Ayres and Paskey here but, for the purposes of this article, the important point is that he says there was no resurrection scene in the script. 

Also, These Are The Voyages, Season Two, goes into detail on the evolution of the script and there is no mention of Leslie returning from the dead.

Furthermore, the nature of the creature’s attack makes a miracle cure improbable. When Kirk asks for the autopsy report on the first two dead crewmembers, McCoy replies: “You saw their color. There wasn’t a red corpuscle left in their bodies.” McCoy is good but even he can’t save someone in that condition and already dead.

It is just possible, of course, that someone on the production staff ran into Paskey on set and said “Hey, you die in the next episode, but don’t worry because they bring you back to life.” Paskey was in A Private Little War, produced just before Obsession, so maybe that happened. 

But it is more likely that the resurrection tale is a good story that did not actually happen. 

Postscript

The character’s name should, arguably, be spelled “Lesley.” The only time the name appeared in the credits was in The Alternative Factor, and that spelling was used.

However, Leslie was supposedly named for William Shatner’s eldest daughter, Leslie Carol Shatner, and for that reason and because fandom has settled on the “Leslie” spelling, I went with that here.