Star Trek: Season 1, Episode 5

The Enemy Within (6 Oct. 1966)

TV Episode  -   -  Action | Adventure | Sci-Fi
Your rating:
    1 2 3 4 5 6 7 8 9 10 -/10 X  
Ratings: 7.8/10 from 1,276 users  
Reviews: 14 user | 10 critic

A transporter malfunction splits Captain Kirk into two halves: one meek and indecisive, the other violent and ill tempered. The remaining crew members stranded on the planet cannot be beamed up to the ship until a the problem is fixed.



, (created by)
0Check in

Watch Now

$0.00 with Prime Instant Video


Editors' Spotlight

IMDb Picks: March

IMDb's editors share the movies and TV shows they are excited to see in March.

User Lists

Related lists from IMDb users

a list of 30 titles
created 19 Aug 2012
a list of 49 titles
created 22 Jan 2013
a list of 21 titles
created 23 Jan 2013
a list of 25 titles
created 19 Mar 2013
list image
a list of 10000 titles
created 5 months ago

Related Items

Search for "The Enemy Within" on

Connect with IMDb

Share this Rating

Title: The Enemy Within (06 Oct 1966)

The Enemy Within (06 Oct 1966) on IMDb 7.8/10

Want to share IMDb's rating on your own site? Use the HTML below.

Take The Quiz!

Test your knowledge of Star Trek.
« Previous Episode | 6 of 80 Episodes | Next Episode »





Episode complete credited cast:
Ed Madden ...
Fisher (as Edward Madden)
Garland Thompson ...
Jim Goodwin ...


While beaming back aboard the Enterprise, a transporter malfunction results in two vastly different Captain Kirks being beamed aboard. His personality has in effect been split into two. One Captain Kirk is weak and indecisive, fearful of making any kind of decision; the other is a mean-spirited and violent man who likes to swill brandy and force himself on female crew members. Meanwhile, as Scotty struggles to repair the transporter, the landing party is stuck on the planet below with temperatures falling rapidly. Written by garykmcd

Plot Summary | Plot Synopsis


See all certifications »




Release Date:

6 October 1966 (USA)  »

Company Credits

Show detailed on  »

Technical Specs


Sound Mix:


Aspect Ratio:

1.33 : 1
See  »

Did You Know?


This takes place in 2266. See more »


This episode begins with the Captain down on the planet's surface wearing a gold shirt with no insignia. When he beams up to the Enterprise, he is still wearing a gold shirt with no insignia, and his "evil half" also transports in wearing the same: a gold shirt without any insignia. Scotty offers to walk the Captain to his quarters and, miraculously, when we cut to the Captain and Scotty in the corridor, the Captain's shirt has sprouted an insignia as has the evil twin's shirt when he walks into Dr. McCoy's medical bay. See more »


Wilson: What happened?
Fisher: I took a flop.
Wilson: Onto what?
Fisher: I don't know. Some kind of yellow ore.
See more »


Referenced in Star Trek: The Next Generation: Datalore (1988) See more »


Theme From Star Trek
Written by Alexander Courage
See more »

Frequently Asked Questions

This FAQ is empty. Add the first question.

User Reviews

Clearly a stumble for the series
5 December 2006 | by (Bradenton, Florida) – See all my reviews

Of the early episodes, this is one that was poorer than average. This isn't to say that it was bad (no, that would be CHARLIE X), but it definitely was sub-par. Why? Well, it was the first episode where William Shatner was allowed to chew the scenes--with over-acting galore! Shatner plays dual roles--an evil id-like Captain and a wussy and indecisive Captain. It turns out that the real captain had himself divided into the two halves and the problem was to first identify that there were two Kirks (people just thought the real one had gone nuts) and then figure out how to re-integrate them. All the meanwhile, a crew is stuck on an icy and craptastic planet awaiting transportation back to the ship (note--they must have forgotten that they had the Galileo shuttle craft). A watchable but not especially memorable episode that features overacting--and then some.

5 of 33 people found this review helpful.  Was this review helpful to you?

Message Boards

Recent Posts
Amok Time: T'Pau was Lied To tommy-john-watson
Mistake in Amok time stanmvp48
Mr. Spock's legacy, who has copied him? tangojazz
The Enemy Within maxshalamar
New to Star Trek. Just finished season 1 baremu
Can You Help Me Find Episode? jojomack2006
Discuss The Enemy Within (1966) on the IMDb message boards »

Contribute to This Page

Create a character page for: