Kirk and Spock must travel into the past in order to correct a change that will alter history.

A transporter mishap swaps Captain Kirk and his companions with their evil counterparts in a parallel universe. In the so-called Mirror Universe, the Enterprise is a ship of the Terran Empire, an organization as evil as the United Federation of Planets is benevolent.

Despite the earlier Romulan war, the Romulans have never been seen in person. The Enterprise, in pursuit of a Romulan aggressor, makes a discovery that causes suspicion about a senior crew member.

The Enterprise picks up a crew of genetic supermen from the 20th century... and their leader, Khan, plans to create a new empire.

The Enterprise must protect a very important shipment of grain from both Klingons and some adorable creatures called tribbles.

First Officer Spock returns to his home world for a brutal Vulcan mating ritual.

The starship Enterprise and its heavily-damaged sister ship, the USS Constellation, must work together to stop an alien planet-killing machine headed for the heart of Federation territory.

The Enterprise must transport dignitaries to a peace conference, with an assassin on the loose.

Kirk investigates a series of grisly murders on a mining planet that are the work of a seemingly hostile alien creature.

Apparently summoned to Star Base 11, Kirk, Spock and McCoy visit a former Enterprise Commander, the paralyzed and horribly disfigured Christopher Pike. Uncharacteristically, Spock commandeers the Enterprise, then turns himself in for court martial.

Spock's court martial reveals the actions of Captain Pike on his previous visit to Talos IV, where the powerful Talosians tried to persuade Pike to breed with women provided for the purpose.

The Federation and the Klingon Empire teeter on the brink of war as Kirk investigates Organia, a humble planet, inhabited by pacifists, that is unwittingly caught in the middle.

Threatened by the sinister captain of a powerful alien vessel, Kirk claims that the Enterprise carries a powerful explosive which will destroy both ships. The move produces unexpected actions from the alien adversary.

The Enterprise arrives at a planet to establish diplomatic relations and finds itself in the middle of a "peaceful" war that threatens to destroy the ship.

A skeleton Enterprise crew are assigned to test a revolutionary computer system that is given total control of the ship.

With both their ships held captive by powerful beings, Kirk and the captain of the alien vessel are placed on an asteroid to fight for their lives and the lives of their crews.

In a freak accident the Enterprise is sent back to 20th century Earth, and must find their way back without changing history.

An alien virus strips the enterprise crew of their inhibitions, causing chaos as each crew member is overcome by hidden emotions. Meanwhile, the Enterprise is being pulled inexorably into a nearby planet's gravity well.

The Enterprise crew try to rescue colonists from deadly radiation, but instead encounter strange alien spores that seem to offer paradise.

When Enterprise encounters a Force Field at the edge of the Galaxy, one of the crew members psionic abilities are accelerated to God like proportions causing him to become a powerful murderous being.

The Enterprise visits a planet with an Earth-like 1920s gangster culture.

The crew of the Enterprise are on a secret mission to steal a Romulan cloaking device.

Split by a transporter malfunction into two beings with very different personalities, the resulting twin Captain Kirk proves that neither a purely evil nor a sweetly good captain can survive without the missing half.

Crash landing on a planet populated by hostile giants, the 7-man crew of the shuttlecraft Galileo find themselves unable to communicate with the enterprise or to escape the planet's atmosphere.

Kirk, Spock and McCoy are trapped in two parts of another planet's past - a world threatened with destruction when its sun goes supernova.