- The original USS Enterprise shuttlecraft Galileo is incinerated and destroyed. Fortunately, the five crew members on board are saved before its destruction via the transporter. (TOS: "The Galileo Seven")
- Commodore Jose I. Mendez replaces Commodore Stone as port master of Starbase 11. (TOS: "Court Martial", "The Menagerie, Part I")
- Fleet Captain Christopher Pike is taken by Commander Spock and the USS Enterprise to planet Talos IV, goes into retirement, and lives with Vina in illusory bliss. (TOS: "The Menagerie, Part I", "The Menagerie, Part II")
- The Enterprise visits a mysterious planet in the Omicron Delta region for some much needed shore leave. However, the planet is discovered to be more than the isolated world it appears to be. The planet contains multiple fantasy and wish fulfillment elements found in the crew's minds. Dr. Leonard McCoy is believed to be killed by an illusory Black Knight. After Captain Kirk and Commander Spock come into contact with the planet's caretaker, McCoy is revived and the Enterprise crew is ultimately able to rest and relax before departing. (TOS: "Shore Leave")
- The Federation observation outpost on planet Cestus III is destroyed which leads the USS Enterprise to make first contact with the Gorn, who are responsible for the outpost's destruction as well as the deaths of two Enterprise crewmen, because the Gorn claim the outpost was in their territory. The Enterprise also makes first contact with the Metrons, who become impressed with Humanity when Captain James T. Kirk shows mercy and spares the life of a Gorn captain after the Metrons set up an arena-style conflict between the two of them. (TOS: "Arena")
- The USS Enterprise uncovers the truth behind the disappearance of the starship Archon that had been lost a hundred years earlier, when it visited the planet Beta III. The Enterprise is responsible for the destruction of the computer known as Landru which had ruled Beta III as a despot for 6,000 years. The ship leaves behind its sociologist Lindstrom and a team of specialist to restore that planet's culture to a more Human form. (TOS: "The Return of the Archons")
- Ensign Pavel Chekov joins the crew of the USS Enterprise. Before the end of the year, Chekov becomes chief navigator. (TOS: "Catspaw", Star Trek II: The Wrath of Khan)
- The SS Botany Bay is discovered by the USS Enterprise in the Mutara sector after drifting in space for 271 years. (TOS: "Space Seed")
- The Treaty of Organia is signed by the Klingon Empire and the United Federation of Planets, thereby preventing a destructive conflict between the two powers and paving the way for further approaches. (TOS: "Errand of Mercy", "The Trouble with Tribbles")
- Helmsman Hikaru Sulu's command console explods in his face aboard the USS Enterprise and Doctor Leonard McCoy accidentally gives himself an overdose of cordrazine which, although not generally revealed, nearly leads him to change history erasing the Federation and Starfleet from existence. (TOS: "The City on the Edge of Forever")
- Denevan neural parasites invade the Deneva colony. Kirk and the crew of the USS Enterprise discover their weakness and destroy them, ending the spread of mass insanity. (TOS: "Operation -- Annihilate!")
- Although not generally revealed, the USS Enterprise discovers warp drive inventor Zefram Cochrane, long believed dead, alive on a remote planetoid in the Gamma Canaris region. (TOS: "Metamorphosis")
- The USS Constellation is destroyed by eliminating an alien planet killer. Commodore Matthew Decker and his entire crew are killed by the planet killer. (TOS: "The Doomsday Machine")
- A transporter accident brings four USS Enterprise personnel from the primary universe to the mirror universe. The primary Kirk encourages the mirror Spock to start a revolution against the Terran Empire. This eventually leads to the conquest of that Empire by the Klingon-Cardassian Alliance in the late 23rd century. (TOS: "Mirror, Mirror"; DS9: "Crossover")
- The population of the Federation experimental colony on planet Gamma Hydra IV is killed from rapid aging caused by radiation from a rogue comet. The USS Enterprise landing party, sent to investigate, also suffers from the rapid aging, except for Ensign Chekov, including the ship's four senior officers and which results in the death of a science division lieutenant. Fortunately Kirk, Spock, Dr. McCoy, and Chief Engineer Lieutenant Commander Montgomery Scott are cured of the rapid aging when McCoy, with the help of Spock, Nurse Christine Chapel, and Dr. Janet Wallace, discover an adrenaline-based cure. (TOS: "The Deadly Years")
- Dr. Janice Lester leads an expedition of scientist to Camus II to investigate the civilization that once existed on that planet. (TOS: "Turnabout Intruder")
- The Klingons provide the inhabitants of Neural with firearms, trying to influence local politics. (TOS: "A Private Little War")
- Nimbus III is jointly established as the "Planet of Galactic Peace" by the Romulan Star Empire, the United Federation of Planets, and the Klingon Empire. (Star Trek V: The Final Frontier)
- Except for Captain Ronald Tracey, the entire crew of the USS Exeter is killed by an unknown disease, which turns them into dehydrated crystals composed of their base minerals, while in orbit around planet Omega IV. (TOS: "The Omega Glory")
- This is the third year of Captain James T. Kirk's first five-year mission. (VOY: "Q2")
- A bottle of Chateau Picard produced this year is shared by the senior officers of the USS Enterprise-E after Data's death. (Star Trek Nemesis)
- Kirk claims to Zefram Cochrane that as of 2267, "We're on a thousand planets and spreading out." (TOS: "Metamorphosis")
- "The Galileo Seven"
- "Court Martial"
- "The Menagerie, Part I"
- "The Menagerie, Part II"
- "Shore Leave"
- "The Squire of Gothos"
- "The Alternative Factor"
- "Tomorrow is Yesterday" (in part)
- "The Return of the Archons"
- "A Taste of Armageddon"
- "Space Seed"
- "This Side of Paradise"
- "The Devil in the Dark"
- "Errand of Mercy"
- "The City on the Edge of Forever" (in part)
- "Operation -- Annihilate!"
- "Friday's Child"
- "Who Mourns for Adonais?"
- "Amok Time"
- "The Doomsday Machine"
- "Wolf in the Fold"
- "The Changeling"
- "The Apple"
- "Mirror, Mirror"
- "The Deadly Years"