In the throes of his Pon Farr mating period, Spock must return to Vulcan to meet his intended future wife, betrothed from childhood.

A powerful being claiming to be the Greek god Apollo appears and demands that the crew of the Enterprise disembark onto his planet to worship him. Director Marc Daniels

A powerful artificially intelligent Earth probe, with a murderously twisted imperative, comes aboard the Enterprise and mistakes Capt. Kirk for its creator.

A transporter accident places Captain Kirk's landing party in an alternate universe, where the Enterprise is in the service of a barbarically brutal empire.

Primitive inhabitants of Gamma Trianguli VI worship a god who orders them to kill visitors from the Enterprise.

The USS Enterprise encounters the wrecked USS Constellation and its distraught commodore who's determined to stop the giant planet-destroying robot ship that killed his crew.

Very alien visitors to our galaxy attempt to connect with human consciousness but miss, winding up tapping into the regions of human nightmares instead.

Harry Mudd returns with a plot to take over the Enterprise by stranding the crew on a planet populated by androids under his command.

While returning to the Enterprise aboard the shuttlecraft, Kirk, Spock, McCoy and a seriously ill Federation diplomat find themselves kidnapped by an energized cloud.

The Enterprise hosts a number of quarrelling diplomats, including Spock's father, but someone on board has murder in mind.

The Federation clashes with the Klingon Empire over mining rights to Capella IV. A sudden coup between its warrior-minded inhabitants forces Kirk's party to flee with the now dead leader's pregnant wife.

The crew of the Enterprise contracts a strange disease that causes rapidly accelerated aging.

Capt. Kirk obsessively hunts for a mysterious cloud creature he encountered in his youth.

Kirk and the Enterprise computer become detectives after Scotty is accused of murdering women on a pleasure planet.

To protect a space station with a vital grain shipment, Kirk and the crew must deal with Federation bureaucrats, a Klingon battle cruiser and a peddler who sells furry, purring, voracious little creatures as pets.

Kirk, Uhura and Chekov are trapped on a planet where abducted aliens are enslaved and trained to perform as gladiators for the amusement of bored, faceless aliens.

The crew of the Enterprise struggles to cope with a planet of imitative people who have modeled their society on 1920s gangsters.

The Enterprise encounters a gigantic energy draining space organism that threatens the galaxy.

Peaceful, primitive peoples get caught up in the struggle between superpowers, with Kirk unhappily trying to restore the balance of power disrupted by the Klingons.

The Enterprise is guided to a distant, long-dead world where survivors of an extremely ancient race - existing only as disembodied energy - desiring the bodies of Kirk, Spock and astro-biologist Ann Mulhall so that they may live again.

Looking for a missing Federation cultural observer, Kirk and Spock find themselves on a planet whose culture has been completely patterned after Nazi Germany.

Galactic alien scouts hijack the Enterprise for a return voyage to their home galaxy and a prelude to invasion. Kirk's only advantage is that they're not fully adapted to the human form they've taken on.

Responding to a distress signal, Kirk finds Captain Tracey of the U.S.S. Exeter violating the prime directive and interfering with a war between the Yangs and the Kohms to find the secret of their longevity.

Kirk and a sub-skeleton crew are ordered to test out an advanced artificially intelligent control system - the M-5 Multitronic system, which could potentially render them all redundant.

The Enterprise crew investigates the disappearance of a ship's crew on a planet that is a modern version of the Roman Empire.

While back in time observing Earth in 1968, the Enterprise crew encounters the mysterious Gary Seven who has his own agenda on the planet.