Stardate: 5373.4 Spock travels back in time to prevent his death as a young Vulcan.

Stardate: 5392.4 Cyrano Jones introduces tribbles that cannot reproduce.

Stardate: 4187.3 Spock, Sulu, and Uhura discover a time capsule from an ancient and technologically advanced race. However, it draws some unwanted attention.

Stardate: 6770.3 With Commodore Robert April (the first commander of the Enterprise) on board, Kirk pursues a ship plunging into a supernova, and enters a universe where time runs backwards.

Stardate: 5267.6 The Enterprise crew must work with Klingons to escape from a pocket universe.

Stardate: 5143.3 The Enterprise finds a long-lost explorer.

Stardate: 5275.6 Dr. McCoy is arrested and held responsible for causing a plague that ravaged the planet Dramia II, where he performed a mass-innoculation 19 years earlier.

Stardate: 5371.3 The crew of the Enterprise races to find a way to stop a cloud from destroying inhabited planets.

Stardate: 5577.3 The Enterprise crew begins to shrink after radiation exposure.

Stardate: 5501.2 Telepathic aliens put Kirk, Spock and McCoy in a zoo.

Stardate: 5521.3 In orbit around a dead star, the Enterprise comes across a huge starship inhabited by a parasitic life form that threatens the entire ship.

Stardate: 5483.7 Female crew members must take over the Enterprise when the men are incapacitated by a race of sirens.

Stardate: 6334.1 With Spock stricken down by a fatal disease, the Enterprise must track down the drug that can cure him before it is too late.

Stardate: 5499.9 While exploring the planet Argo, Kirk and Spock are turned into water breathers.

Stardate: 3183.3 The computer of the Enterprise gains partial sentience and starts playing practical jokes on the crew.

Stardate: 6063.4 The Enterprise runs into a being that once visited Earth and influenced the Mayan culture.

Stardate: 4978.5 Space con artist Harry Mudd returns, selling a fake love potion.

Stardate: 5591.2 Kirk returns to the "shore leave" planet, but it's not as peaceful as it was when they last saw it.

Stardate: 5683.1 Kirk and Spock are recruited for a heist to recover a stolen relic, which if not recovered could spark an galactic jihad.

Stardate: 5554.4 A race of plant people, and their master, have a plan to force peace onto the galaxy.

Stardate: 7403.6 The Enterprise crew is joined by a unpredictable alien called Ari bn Bem, an independent observer from the planet Pandro.

Stardate: 1254.4 At the center of the galaxy, the Enterprise discovers a race of powerful aliens.