09/15/67 -- Stardate: 3372.7
Under the stress of his first pon far, Spock returns to Vulcan to wed his childhood bethroted, only to find that she has chosen another and forces Spock into a ceremonial fight to the death with Kirk.
Who Mourns for Adonis
09/22/67 -- Stardate: 3468.1
The Enterprise crew is trapped on a planet by the Greek god Apollo, who wants humans to stay on the planet to worship him.
09/29/67 -- Stardate: 3451.9
The Enterprise encounters Nomad, a small mutated Earth probe that has been destoying planets in its path in an attempt to sterilize the imperfect life forms on them.
10/06/67 -- Stardate: Unknown
While transporting during an ion storm, Kirk, McCoy, Scott, and Uhura are switched with evil counterparts in a parallel universe, and it is up to the parallel Spocks to get their respective crew members back.
10/13/67 -- Stardate: 3715.0
The seeming paradise found by the Enterprise on Gamma Trianguli VI is really controlled by a computer called Vaal, which tries to destroy the Enterprise to prevent intervention from the outside.
The Doomsday Machine
10/20/67 -- Stardate: 4204.9
A giant robot ship wandering through the galaxy destroying everything in its path cripples the starship Constellation and then turns on the Enterprise.
10/27/67 -- Stardate: 3018.2
The Enterprise finds a haunted castle inhabited by tiny aliens who have transformed themselves into a witch and a warlock and imprisoned some of the Enterprise crew.
11/03/67 -- Stardate: 4513.3
An android masquerading as an Enterprise crew member hijacks the ship and delivers it to Harry Mudd, who has developed a race of beautiful android women.
11/10/67 -- Stardate: 3219.4
The shuttlecraft Galileo, carrying Kirk, Spock, McCoy, and Federation Commissioner Nancy Hedford, is drawn to a small planet by a mysterious cloud, which turns out to be a creature that has been caring for shipwrecked warp drive inventor Zefram Cochrane.
Journey to Babel
11/17/67 -- Stardate: 3842.3
The Enterprise is transporting delegates to a Federation conference, when Spock's father, Ambassador Sarek, becomes ill and requires a transfusion from Spock.
12/01/67 -- Stardate: 3497.2
Attempting to negotiate a mining treaty on Capella IV, the Enterprise crew becomes involved in a Klingon-instigated civil war and must save the pregnant wife of the planet's leader.
The Deadly Years
12/08/67 -- Stardate: 3478.2
Kirk, Spock, McCoy, and Scott undergo accelerated aging after being exposed to radiation on a planet, but Chekov isn't affected and Dr. McCoy must find out why in order to cure the others.
12/15/67 -- Stardate: 3619.2
Kirk is obsessed with trying to kill a cloud-like vampire creature similar to one that killed Kirk's commanding officer, Captain Garrovick, 11 years earlier.
Wolf in the Fold
12/22/67 -- Stardate: 3614.9
Scott is accused of the brutal murder of several women who were really killed by a non-corporeal creature known in Earth's past as Jack the Ripper.
The Trouble with Tribbles
12/29/67 -- Stardate: 4523.3
When the Enterprise stops at the K-7 space station to pick up a shipment of a new type of grain, trader Cyrano Jones introduces the Enterprise crew to tribbles, cute furry creatures that multiply so rapidly that they almost fill the Enterprise to its seams with fur.
The Gamesters of Triskelion
01/05/68 -- Stardate: 3211.7
While surveying an uncharted planet, Kirk, Uhura, and Chekov are transported to the planet's surface, where they are forced to be gladiators in combats staged for the pleasure of unseen aliens.
A Piece of the Action
01/12/68 -- Stardate: 4598.0
The Enterprise crew investigates the progress made by a planet visited by a Federation ship over 100 years earlier, and find that a book on the Chicago mobs of 1930's Earth has served as the role model for the planet's development.
The Immunity Syndrome
01/19/68 -- Stardate: 4307.1
The Enterprise is sent to investigate a giant amoeba-like creature that has killed all life on Starbase 6 and the Vulcan-crewed starship Intrepid, and Spock penetrates the amoeba in a shuttlecraft.
A Private Little War
02/02/68 -- Stardate: 4211.4
The Enterprise crew becomes involved in a civil war on Neural, and must arm the tribe of an old friend of Kirk's in order to maintain a balance of power with the opposing tribe that is receiving arms from the Klingons.
Return to Tomorrow
02/09/68 -- Stardate: 4768.3
On a long-dead planet, the Enterprise finds three disembodied entities who ask for assistance in constructing android bodies for their brains, but one of the entities tries to steal Spock's body instead.
Patterns of Force
02/16/68 -- Stardate: 2534.0
On a routine visit to the planet where a Federation historian has been stationed, the Enterprise finds that the planet's culture has been patterned after Nazi Germany.
By Any Other Name
02/23/68 -- Stardate: 4657.5
The Enterprise crew is captured by a group of Kelvans from the Andromeda Galaxy, who are scouting this galaxy for possible colonization.
The Omega Glory
03/01/68 -- Stardate: Unknown
The Enterprise crew finds the empty starship Exeter in orbit around Omega IV, and beams down to discover that the Exeter's captain has provided advanced weapons to the Kohms in their battle against the Yangs.
The Ultimate Computer
03/08/68 -- Stardate: 4729.4
The Enterprise is fitted for tests of an advanced computer containing the erratic brain patterns of its inventor, Dr. Richard Daystrom, and begins a real attack on other starships during what is supposed to be a war game.
Bread and Circuses
03/15/68 -- Stardate: 4040.7
The Enterprise crew encounters the abandoned S.S. Beagle in orbit around Planet 892-IV, and beams down to find that its captain has introduced a Roman-like gladiator culture to the planet.
03/29/68 -- Stardate: Unknown
The Enterprise returns to the 20th Century to learn how Earth survived its atomic age, and runs into Gary Seven, a human who has been raised in a distant galaxy to help the Earth overcome its self-destructive tendencies.