Both humans and Klingons have been lured to a planet by a formless entity that feeds on hatred and has set about to fashion them into a permanent food supply for itself.


(as Marvin Chomsky)


(created by),

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Episode complete credited cast:
David L. Ross ...
Lt. Johnson (as David Ross)
Mark Tobin ...


Having found a Federation colony of 100 people completely destroyed, Kirk and the Enterprise have to deal with a nearby Klingon vessel which they believe must be responsible for the colony's destruction. When the Klingon ship is disabled, they, in turn, assume they were attacked by the Enterprise. There is obvious tension between the Enterprise crew and its Klingon enemies. Unbeknown to Kirk and his Klingon counterpart, Kang, this is the work of an alien being that gets its energy from the friction and emotions between sentient beings. The natural animosities between the two parties feed its appetites. When the creature is beamed aboard the Enterprise, it purposely creates tension among the crew, to its benefit. The situation eventually forces Kirk and Kang to work together to defeat it. Written by garykmcd

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Release Date:

1 November 1968 (USA)  »

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Aspect Ratio:

1.33 : 1
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Did You Know?


This episode was originally written with John Colicos' Kor (from Star Trek: Errand of Mercy (1967) as Kirk's Klingon adversary. Although Mr. Colicos really wanted to reprise that role, he was in Europe making Anne of the Thousand Days (1969), and was unavailable. The part was recast with Michael Ansara as "Kang". See more »


Just before Chekov forces a kiss on Mara, we see in the close-up shots of her that she is wearing lipstick. Kirk and Spock then arrive and intervene, and in the cutaway shots of Mara during Kirk's subsequent speech, the lipstick is gone. Then Kirk has Spock take her, and as she and Spock exit frame, we see she's wearing lipstick again. See more »


Kang: We need no urging to hate Humans. But for the present, only a fool fights in a burning house.
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Referenced in The Simpsons: Treehouse of Horror (1990) See more »

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User Reviews

A hate parasite
25 May 2014 | by (Buffalo, New York) – See all my reviews

The Organian forced peace may have been obtained in a previous episode, but things are still tense between the Federation and the Klingon Empire. Anything can set it off and in this episode some thing nearly does.

Some of the Star Trek regulars are trapped in a section of the Enterprise that has been sealed off. Futuristic weapons have been taken away and our regulars have been given swords. That puts them at a disadvantage with the warrior society the Klingons have since they prize skill in hand to hand type combat. Still our guys hold their own.

It soon becomes apparent that something is creating this competition and is feeding off the energy of hate that is created by the humans and Klingons. There's an old expression that feuds themselves take on a life of their own and sometimes it's forgotten why they start. This episode gives credence to that idea.

Michael Ansara plays the leader of the Klingons and he's well suited to the part of Kang. Ansara repeated his role in future Star Trek shows. He and William Shatner have to realize there's a common enemy out there.

It's an interesting allegory and can be applied to the state of this world's politics then and now.

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