Star Trek: Day of the Dove

Episode: "Day of the Dove"
Series: Star Trek: The Original Series
Season 3, Episode 7
Original Air Date: November 1, 1968

via Wikipedia

Distress calls bring both the Enterprise and a Klingon ship to Beta XII-A.  The malevolent superior entity that lured them plays puppeteer with both parties, fueling tensions.  The Klingons are brought aboard the ship.  Unwilling to be docile prisoners, they take over engineering.  All the while, the entity allows neither side to gain a permanent upper hand.  In time, our heroes deduce that this evil spirit feeds off of conflict and they can only defeat it by making peace with the Klingons.

Symbolism is heavy-handed indeed.  A memorable exchange during the initial Federation/Klingon confrontation:

Kirk: Go to the devil.
Klingon Commander Kang: We have no devil, Kirk.  But we understand the habits of yours.

Later, Kirk accuses the entity of having meddled in the affairs of others before, a perpetual force of evil in the universe.  Apparently the original script had the Klingons and Enterprise crew singing songs in a peace march.  Thankfully, sensibility prevailed and laughter was used to drive the entity away.

The heavy-handedness aside, "Day of the Dove" is a good episode for the development of the Klingons.  As with the Romulans in "The Enterprise Incident," we have glimpses of better cultural understanding amid the tensions:

Kirk (to Mara, Kang's wife, after Kirk threatens to kill her as a bluff to Kang): The Federation doesn't kill or mistreat its prisoners.  You've been listening to propoganda... fables.

Mara (later, to Kirk): We have always fought.  We must.  We are hunters, Captain, tracking and taking what we need. 

The end, while not hopeful exactly, does offer a possible path to long-term peace.

*****

via Memory Alpha

Michael Ansara (Kang) was born April 15, 1922 in Syria.  His family emigrated to the United States when he was two years old.  He took acting classes as a way to overcome shyness, then fell in love with it.

His long career ranged from Biblical epics to westerns to science fiction.  He played Judas in 1953's The Robe.  He had the lead roles in two 1950s TV series: Broken Arrow and Law of the Plainsman.  He played Kane in the Buck Rogers TV series.  He reprised the role of Kang in Deep Space Nine and Voyager episodes.  Hardly needing to add more to his geek cred, he was also the voice of Dr. Freeze for Batman: The Animated Series and its spinoffs.

While making Broken Arrow, the publicity department set Ansara up on a date with Barbara Eden, later of I Dream of Jeannie fame.  The two were married for 16 years, divorcing in 1974.  Their only son, Matthew, died of a heroin overdose in 2001.  Michael Ansara died in 2013 after a long illness.