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 1,240 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

Sundance 2015

Watch our IMDb & AIV Sundance Studio Interviews with Keith Simanton

User Lists

Related lists from IMDb users

a list of 79 titles
created 19 May 2011
a list of 30 titles
created 19 Aug 2012
a list of 25 titles
created 19 Mar 2013
a list of 44 titles
created 03 Jun 2013
a list of 30 titles
created 8 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?


The only Star Trek program written by Richard Matheson, a Twilight Zone (1959) legend who wrote a previous William Shatner vehicle, Twilight Zone: Nightmare at 20,000 Feet (1963). See more »


Evil Kirk's phaser changes between cuts in the shoot-out in Engineering. See more »


Lt. Cmdr. Leonard 'Bones' McCoy, M.D.: He's dead, Jim.
See more »


Referenced in Breaking In: White on White on White (2011) See more »

Frequently Asked Questions

This FAQ is empty. Add the first question.

User Reviews

Psychological "thriller"
29 May 2009 | by (The San Francisco Bay Area) – See all my reviews

This episode explores the "duality" of man. The ying-yang of how and what drives and keeps a man sane. Shatner is challenged as an actor to give us two extremes of one character; a bipolar portrayal, so to speak. The audience witnesses the theory of what drives a man, and that which stables his more aggressive tendencies.

Is the premise true? A single Star Trek episode certainly cannot answer nor adequately extrapolate in a single dramatization, but it is an interesting character study from a purely psychological point of view. While other TV shows were concerned about what dad would do when he got home, Star Trek was examining deep human issues on all levels emotional and scientific levels (or as could be expected by a dramatization of science fiction).

Spock sums up the episode's and author's thrust near the end. And Kirk makes the final observation after being thrust into a kind of psychological rehabilitation courtesy Scotty's "finicky piece of machinery", remarking on a man's self observance. The idea here is to view ones' various personality traits, reign them in, then expunge them to reconfigure the subject back to psychological norms.

Not an episode that comments on any real deep social issues, but one that asks the viewer to look at a fractured man and his reconstitution.

3 of 4 people found this review helpful.  Was this review helpful to you?

Message Boards

Recent Posts
Body Count GUrsus
All Time Worst Pickup Line lmphilbric
Fans of Let This be Your Last Battlefield... jillian.diamond
Things that bugged you when you watched as a kid flashgordan
William Shatner as Captain Kirk, A++ gavbrown01
Why "What Little Girls Are Made Of" is such a great ep gavbrown01
Discuss The Enemy Within (1966) on the IMDb message boards »

Contribute to This Page

Create a character page for: