One Degree Of Separation / Star Trek

• While Star Trek: The Next Generation began with Q confronting Captain Picard to interrupt mankind's trek through the stars, he only popped up in Deep Space Nine and Voyager by circumstances.
  • Q made his sole on-screen visit to space station Deep Space 9 as a result of Vash stopping there after breaking up with him.
  • Some 70,000 light years from home, the starship Voyager inadvertently set free a rogue Q (Quinn) who had been imprisoned centuries prior, leading the familiar Q to appear on the ship to intercept him. Taking a fancy to Captain Janeway, this would not be the last time Q would stop by.
• As a result of a Borg temporal incursion, human warp drive inventor Zefram Cochrane came into contact with crewmembers of the Enterprise-E, with Riker and LaForge acting as co-pilots for his historic warp flight in order to fix establish history. Decades later, Cochrane worked with Henry Archer, father of Jonathan Archer, the future captain of United Earth starship Enterprise, vital to the formation of the United Federation of Planets. Well over a century after having went missing presumed dead, Cochrane was found by Kirk and crew of the first Federation starship named Enterprise.
• Former ship's surgeon of the original Enterprise, Admiral Leonard McCoy took a tour of the Enterprise-D, escorted by Lieutenant Commander Data. A couple of years later, the ship accomodated Sarek, who Captain Picard met in passing at the ambassador's son's wedding. A couple years later still, Picard and Data go undercover to confront Spock, son of Sarek, on Romulus, with Picard sharing with Spock the mind of his recently deceased father. The Enterprise-D then retrieves former Enterprise chief engineer Montgomery Scott, who had been lost in the transporter for decades. Ultimately, the Enterprise-D's final voyage sees Picard find James T. Kirk, the captain of the Enterprise who Spock had likened Picard to earlier. Funnily enough, Kirk ponders aloud to Picard what Spock would make of him taking another dangerous mission.
• Guinan, bartender of the Enterprise-D's Ten Forward, is an old friend of Picard, even older than he first believed, having first met his time travelling future self in the 19th century. In the interim, Guinan, escaping her planet's assimilation by the Borg, was among the refugees picked-up by the Enterpise-B, meeting Pavel Chekov.
• The Enterprise-D was the first Starfleet vessel to stop at Deep Space 9 (formerly Terok Nor), the Cardassian space station left to the joint custody of Starfleet and the Bajorans. A couple of years later, Voyager stopped at the station before going on the fateful mission which took the ship to the other side of the galaxy, with Lieutenant Tom Paris saving Ensign Harry Kim from falling for a scam from Quark the bartender.
  • Deep Space 9 commanding officer Benjamin Sisko had first faced Picard, then Locutus of Borg, in the Battle of Wolf 359, making their reunion frosty at first. Joining the station's crew is Chief Miles O'Brien, transfered from the Enterprise.
  • The next time the Enterprise visits the station, several senior staff members stop including Worf, who does not make friends. Meanwhile, DS9 Doctor Julian Bashir visits the Enterprise, receiving assistance from Data and LaForge to examine an alien device.
  • Enterprise First Officer William T. Riker also visited DS9, making the acquiantance of Quark and Lieutenant Dax. The next time Riker shows up, he introduces himself to both Commander Sisko and Major Kira, only that's not Will, but his transporter duplicate Thomas, who is assuming his "brother's" identity to acquire the starship ''Defiant''.
• Border conflicts brought Gul Evek of the Cardassian Fourth Order into contact with the Enterprise-D and DS9. He was last seen pursuing a Maquis raider piloted by Chakotay, future First Officer of Voyager.
• Riker was also summoned to Voyager by Q during the Quinn incident, revealing that Riker owes his existence to the rogue Q who saved his ancestor in the American Civil War. However, he and Quinn's other historical witnesses have their memories of the event wiped.
• Going through several humanoid Trill bodies, the Dax symbiont made the acquiantance of several notable figures. As Emony, Dax met Dr. Leonard McCoy. As Curzon, Dax helped foster peace between the Federation and the Klingons, having befriended the legendary warriors Kor, Kang and Koloth, all of them counted Captain Kirk as a worthy adversary. In Curzon's later life, Dax made a friend in young Starfleet officer Benjamin Sisko. With Curzon's passing, Dax was transfered to a young woman named Jadzia, with the new Jadzia Dax aboard DS9 under Commander Sisko, who continued to call Dax "old man".
• "Trials and Tribbleations" sees the Defiant crew pick up Arne Darvin, actually a Klingon who has been disguised as a human ever since he was rumbled by Kirk in "The Trouble with Troubles". Employing Time Travel to revisit the events of that episode in an attempt to Make Wrong What Once Went Right, Darvin forces the Defiant crew, namely Sisko, Dax, Odo, Worf and Bashir to go undercover on Kirk's Enterprise as the crew clashes with that of Koloth's Klingon battlecruiser on Space Station K7. Dax is all too pleased to see some familiar faces from afar, while Sisko cannot help but approach Kirk while undercover.
• Decades before counting himself as a close friend of Captain Janeway, future Voyager security chief Tuvok served on the Excelsior captained by Hikaru Sulu as well as with Janice Rand, themselves former crew members of Kirk's Enterprise.
• Dr. Lewis Zimmerman invented and adapted his likeness to the Emergency Medical Holographic Program which appears on both Voyager and the Enterprise-E. Seeking to develop a Long-term Medical Holographic Program, he visited DS9 to review Dr. Bashir as a template, interviewing all his friends. Later, stricken by a terminal illness, Zimmerman is hesitantly treated by his "son" from Voyager, with Enterprise Counselor Deanna Troi acting as mediator.
• Reginald Barclay was a member of the Enterprise engineering staff as late as the First Contact incident, allowing him to meet Zefram Cochrane. Later, he joins the project to make contact with the stranded starship Voyager, also counting himself as a close friend of Dr. Zimmerman.
• After returning Voyager home, Janeway is promoted to Admiral, giving her the authority to send Picard on his mission in Star Trek: Nemesis.
• In her youth, Vulcan leader T'Pau was assisted by Captain Archer and T'Pol during a crisis on her planet. Over a century later, she officiated the wedding of Spock.
• Con artist, smuggler, and swindler Harcourt Fenton "Harry" Mudd was a recurring thorn in the side of Captain Kirk and Mr. Spock and, before that, Spock's stepsister Michael Burnham and her captain, Gabriel Lorca of the USS Discovery.
• Star Trek: Picard, set two decades after Nemesis, reveals that Picard is familiar with Voyager's Seven of Nine, who is in turn familiar with Hugh, all having been assimilated and subsequently liberated from the Borg Collective.
• The video game Star Trek: Legacy centers on this trope, with the five Captains (Archer, Kirk, Picard, Sisko and Janeway) all being embroiled in the centuries-spanning machinations of the Vulcan turned Borg T'Uerell.
• Though the origin of the player character in the MMO Star Trek Online varies according to choice of faction, they inevitably end up as a captain in the Federation/Klingon/Romulan Alliance (now accepting the Dominion) and come into contact with so many Trek faces that it would be easier to list who they have not met. People you encounter include temporal agent Daniels, Geordi LaForge, former Klingon Chancellors Gowron and Martok, Kira Nerys, Odo, Julian Bashir, Quark, Nog, Rom, Leeta, Garak, Weyoun 10, the Female Changeling, Tuvok, Harry Kim, the Doctor, Seven of Nine, Neelix, Tom Paris, Miral Paris, 0718 of the Kelvin timeline Enterprise, Captain Sylvia "Killy" from the mirror universe, Michael Burnham's Excalbian recreation, a sentient holographic duplicate of Paul Stamets, the resurrected former Klingon Chancellor L'Rell, J'ula (sister of T'Kuvma).
• The Star Trek novel Enterprise: The First Adventure has most of Kirk's Enterprise crew meeting each other before the start of the original series.
• The novel series The Rise And Fall of Khan Noonien Singh involves at least one character from almost every Star Trek episode with characters from the 20th century. Khan (of course), Gary Seven and Roberta Lincoln, Jackson Roykirk, Shaun Christopher and Flint the Immortal from TOS; Guinan, Ralph Offenhouse and Clare Raymond from TNG; Jeffrey Carlson from Deep Space Nine; Rain Robinson and Shannon O'Donell from Voyager.