- Captain James T. Kirk, Commander Spock, and historian Erickson use the Guardian of Forever to observe Federation and Orion history firsthand. (TAS: "Yesteryear")
- Harry Mudd swindles the inhabitants of the planet Ilyra VI by trying to sell them the Starfleet Academy. (TAS: "Mudd's Passion")
- Memory Alpha's memory core is burned out, and all of its personnel, Federation scholars, researchers, and scientists that are there at the time are killed, when the planetoid is attacked by the "lights of Zetar" beings. (TOS: "The Lights of Zetar")
- Lieutenant Mira Romaine begins working to restore the memory core of Memory Alpha. (TOS: "The Lights of Zetar")
- The Federation class J space cruiser Aurora is stolen by Doctor Sevrin and his followers. (TOS: "The Way to Eden")
- The Troglyte miners of the planet Ardana start wearing filter masks to block the mental ill effects of mining zenite. (TOS: "The Cloud Minders")
- Dr. Sevrin and his followers temporarily hijack the USS Enterprise, steal the shuttlecraft Galileo II, and take both into Romulan space so they can get to the planet Eden. (TOS: "The Way to Eden")
- Dr. Sevrin and his follower Adam die on Eden after biting into an acid-saturated fruit. (TOS: "The Way to Eden")
- Dr. Leonard McCoy discovers that Flint, found by the USS Enterprise living on the planet Holberg 917G, has his time as an immortal coming to an end and will soon die, due to his leaving Earth's atmosphere. Although not revealed during his lifetime, as an immortal Flint was known by several historic names including King Solomon, Alexander the Great, Leonardo da Vinci, Johannes Brahms, and interstellar financier Brack. (TOS: "Requiem for Methuselah")
- The USS Enterprise makes first contact with the Excalbians. (TOS: "The Savage Curtain")
- Lieutenant Arex replaces Ensign Pavel Chekov as the USS Enterprise's chief navigator as Chekov was assigned further officer training. (TAS: "The Magicks of Megas-Tu")
- Ensign Walking Bear, a Comanche Native American, is promoted as chief relief helmsman for Lieutenant Sulu aboard the USS Enterprise. (TAS: "How Sharper Than a Serpent's Tooth")
- The USS Enterprise re-establishes contact with the Megans of the planet Megas-Tu as the ship is exploring the galactic core. (TAS: "The Magicks of Megas-Tu")
- Lieutenant M'Ress is assigned to be a relief communications officer for Lieutenant Uhura aboard the USS Enterprise. (TAS: "Mudd's Passion")
- Tuvok begins taking lessons in kal-toh from a Vulcan master. (VOY: "Alter Ego", "Gravity")
- Els Renora is born on Bajor. (DS9: "Dax")
- Keiko Ishikawa's mother is born. (DS9: "Dax")
- The Mantilles colony in the Pallas 14 system is threatened by the cosmic cloud creature. (TAS: "One of Our Planets Is Missing")
- The USS Enterprise discovers an ancient abandoned insectoid starship in orbit around Questar M-17 and makes first contact with a magnetic organism. (TAS: "Beyond the Farthest Star")
- The USS Enterprise uncovers what happened with the Terran geneticist Dr. Stavos Keniclius by finding his fifth generation clone living with the Phylosians. (TAS: "The Infinite Vulcan")
- The USS Enterprise uncovers what happened with the Terra 10 colonists, with whom Earth lost contact in the middle of the 21st century, and help their mutated Terratin descendants relocate to a geologically more stable planet than the one they are found on orbiting the star Cepheus. (TAS: "The Terratin Incident")
- The star Beta Niobe supernovas, destroying the planet Sarpeidon. (TOS: "All Our Yesterdays")
- The asteroid ship Yonada reaches its destination and the Fabrini settle down under the leadership of high priestess Natira. (TOS: "For the World is Hollow and I Have Touched the Sky")
- This is the beginning of the fifth and final year of Captain Kirk's first five-year mission. (VOY: "Q2")
- "Beyond the Farthest Star"
- "Yesteryear" (in part)
- "One of Our Planets Is Missing"
- "The Lorelei Signal"
- "More Tribbles, More Troubles"
- "The Survivor"
- "The Infinite Vulcan"
- "The Magicks of Megas-Tu"
- "Once Upon a Planet"
- "Mudd's Passion"
- "The Terratin Incident"
- "The Time Trap"
- "The Ambergris Element"
- "The Slaver Weapon"
- "The Eye of the Beholder"
- "The Jihad"