Q

Q debuted in "Encounter at Farpoint", where he puts Captain Picard and the Enterprise crew on trial, arguing that humanity is a dangerous race and should be destroyed. When they later save the life of a kidnapped alien, Q agrees to defer judgment, though he hints that it will not be the last time the crew sees him.
In "Hide and Q", he forces the Enterprise crew to participate in a war game against monsters he summoned, then makes a wager with Picard. He grants Commander William Riker the powers of a Q, then promises that if Riker rejects the powers, then Q will leave them alone. Riker uses the powers to save his friends and starts to lose himself to them, but ultimately manages to reject them. Q attempts to go back on his word, but the Q Continuum forcibly recalls him.
In "Q Who", he offers to divest himself of his powers and guide humanity through uncharted regions and prepare it for unknown threats. Picard argues that Q's services are unneeded (and unwanted), and Q rebuts him by teleporting the USS Enterprise to a distant system for their first encounter with the Borg. Unable to resist the Borg, Picard must ask Q to save the ship. Q returns the Enterprise home and tells Picard that other men would rather have died than ask for help. This episode also reveals Q has a past history and hostile relationship with Guinan.
In "Deja Q", Q is punished by the Q Continuum by being made mortal; his committing of an uncharacteristically selfless act (sacrificing his life so that a race attacking him will not destroy the Enterprise) garners the return of his powers. In the same episode, Q says that Picard is "the closest thing in this universe that I have to a friend."
The Q are mentioned in "Devil's Due". A woman named Ardra claims to be the Devil to subjugate a planet, displaying abilities similar to the Q. The crew speculate that she may be a member of the Q Continuum or even Q himself in a disguise before Picard points out Q would not be interested in a planet's economics. Ardra is exposed as a con artist using technology to simulate her powers.
In "Qpid", Q attempts to repay Picard for saving him in "Deja Q" by helping him with his relationship with his ex-girlfriend Vash. He transports everyone to Sherwood Forest and casts himself as the Sheriff of Nottingham, Picard as Robin Hood, the crew as the Merry Men, and Vash as Maid Marian, then challenges them to rescue her. Q and Vash find themselves kindred spirits, and she ultimately decides to go with him and explore the universe together.
In "True Q", Q reveals that a new crew member named Amanda Rogers is actually the daughter of two rogue members of the Q Continuum, then orders her to choose between remaining human and never using her powers, or coming with him to join the Continuum. After using her powers to save a planet, Amanda decides to join the Continuum.
Toward the end of The Next Generation, Q is less antagonistic toward Picard. In "Tapestry", Q apparently saves Picard and helps him better understand himself, giving Picard a chance to avoid the accident that gave him an artificial heart only for Picard to choose dying as himself over living the tedious life he would have lived without the inspiration of his near-death experience (although whether Q actually appeared in this episode or was merely a hallucination Picard experienced during surgery is deliberately left ambiguous).
In "All Good Things", Q reveals that the trial of humanity is not over and displaces Picard through different time periods where a temporal anomaly threatens the existence of humanity. After Picard resolves the situation, Q admits to having helped him find the solution and to having saved him from death. Q departs, stating that the trial of humanity is never over.
In the Star Trek: Deep Space Nine episode "Q-Less", Vash decided to end her partnership with Q. Q follows her to the Deep Space Nine station and attempts to win her back. Q is blamed for a series of power failures, but denies it. Q taunts Commander Benjamin Sisko, only to get punched in the face, shocking him since Picard never did that. The power failures were actually caused by an alien life form disguised as a crystal that Vash was carrying. Q gives Vash his blessing to leave him.
In the Star Trek: Voyager episode "Death Wish", Q pursues a rogue member of the Continuum, later named Quinn, who has been inadvertently released from his asteroid prison by the crew of that ship, and who seeks asylum on Voyager. He demands that Q make him human, as he does not wish to be a member of the Continuum any more, but Q refuses, because Quinn intends to commit suicide if he becomes human. The two parties agree to allow Captain Janeway to mediate their dispute, and after Janeway eventually finds in favor of Quinn, he is made human and then commits suicide. Its subsequently revealed that Q chose to assist Quinn's suicide.
Later, in the Voyager episode "The Q and the Grey", Q reappears on the Voyager, asking Janeway to bear his child. He eventually reveals that the uncertainty and instability caused by Quinn's suicide divided the Continuum, causing a civil war between Quinn's followers (of which Q is a part) and the rest of the Continuum. Q believes that the birth of a new member of the Continuum could revitalize the Q by giving them something new to focus on after millennia of stagnation and boredom. Janeway refuses, and after she and her crew bring about a ceasefire in the Continuum, Q eventually mates with a female Q (Suzie Plakson) with whom he had been involved (referred to in Star Trek novels as 'Lady Q'), producing a son. Their progeny is born conscious and with all the power of any other Q, although lacking adult maturity. Q makes Janeway his godmother.
In the episode "Q2", he appears on Voyager with his immature, rebellious son, who appears as a human teenager (played by John de Lancie's real-life son Keegan de Lancie, and referred to in the novels as "Little Q" or "q"). Q asks Janeway to mentor his son, and the two adults agree that the boy will remain on Voyager, without his powers, and either learn how to be a responsible, accountable, and productive inhabitant of the cosmos, or spend eternity as an amoeba. Eventually, the young Q comes around, but the Continuum is not entirely convinced, so in negotiation with Q, they come to an agreement. Q must eternally guard, observe, and accompany the boy to ensure his proper behavior. Q thanks Janeway for her help by showing her a shortcut to Earth that will shave three years off Voyager's journey. When she asks why he does not just send them directly to Earth, he says it would set a bad example for his son to do all the work for them.
In the Star Trek: Lower Decks episode "Veritas", Q appears in a flashback, challenging the senior crew of the USS Cerritos to an inexplicable 'game' to prove humanity's worth, dressing them up as chess pieces facing a football field filled with anthropomorphic cards and soccer balls. Later in the episode, he appears again to challenge the ensigns to a duel, but he is unceremoniously blown off by Ensign Mariner, who tells him to "go bother Picard." Q follows them anyway, complaining that Picard is always quoting Shakespeare and making wine.
Q returns in season 2 of Star Trek: Picard.[2] In the episode "The Star Gazer", the ship Stargazer is attacked and nearly assimilated by a Borg Queen, forcing Picard to activate the ship's self-destruct mechanism. Just as the ship explodes, Picard abruptly wakes up in a different version of his home. Q appears, initially looking like his younger self before turning himself into an old man to match Picard's age. Q says the trial of humanity is not over, so he's altered history to show Picard "the end of the road not taken."
In the next episode, "Penance", Q acts unusually agitated while claiming this dark, totalitarian future is all Picard's fault, even striking Picard when he complains. This prompts Picard to wonder if Q is unwell. Q admits to saving Picard and his crew from the explosion of the Stargazer and making sure they all remembered the original timeline to give them a chance to change it back. After Q departs, Picard meets his crew and they work with a captured Borg Queen, who can detect temporal anomalies and says this future was caused by a change in Los Angeles in the year 2024.
In the next episode, "Assimilation", Q briefly appears to taunt Picard about how everything was lost because of his fears before disappearing.
In the next episode, "Watcher", Q appears in Los Angeles in 2024, observing a woman working on a planned spaceflight to Europa. He is then surprised to find his powers do not work.
In the next episode, "Fly Me to the Moon", the woman is revealed to be Jean-Luc Picard's ancestor, Renee Picard. Undaunted by the loss of his powers, Q poses as Renee's psychiatrist and tries to convince her to cancel her spaceflight to Europa. When Picard and his crew find out about this, they speculate that this is the change that causes the dark future. Q also meets Dr. Adam Soong and provides him a temporary cure for his daughter Kore's life-threatening illness. Desperate for a permanent cure, Soong agrees to assist Q.
In the next episode, "Two of One", Q instructs Soong to stop Renee from going on her spaceflight, which he attempts by trying to hit her with his car. However, Picard pushes her out of the way and is hit instead and hospitalized by his injuries.
Q is mentioned in the next episode, "Monsters". After recovering, Picard asks Guinan to summon Q to their location so he can question him, remembering Q's unusual behavior in their previous encounter. Guinan reveals that the Q Continuum and her race, the El-Aurians, went to war in the past before making a peace treaty. However, her ritual to summon Q fails.
In the next episode, "Mercy", after Picard and Guinan have been arrested by an FBI agent, Q visits Guinan disguised as an agent, revealing that he is dying and that this whole scenario was just an attempt to give his life meaning. He leaves after saying humans are always stuck in the past, giving Picard inspiration to pry into the agent's past to persuade him to let them go. Q later visits Kore and gives her the permanent cure even though Soong did not fulfill his end of the bargain, allowing her to leave her home and escape her controlling father. The Borg Queen reveals the change that caused the dark future: In the original timeline, Renee found an alien life form on Europa, paving the way for the formation of the Federation. If Renee's flight is prevented, Dr. Adam Soong will eventually rise in power and become ruler of the world.
In "Farewell," after the original timeline is restored, Picard encounters Q in his home after leaving the skeleton key for his younger self to find in the future. Q notes that although Picard had the chance to potentially save his mother and change his own future, he instead accepted himself as he is and absolved himself. Because Picard has chosen himself, he may now be worthy for someone else to choose and he may even give himself the chance to be loved. Q reminds Picard that he'd told Picard that this was about forgiveness: Picard's own forgiveness of himself. Q reminds Picard that he has fixed all of the deaths that Q had caused by altering the timeline aside from Tallinn and Elnor. However, Tallinn was always destined to die in every timeline, but thanks to Picard's intervention, Tallinn had met Renée in this one. Picard asks why Q had taken such an interest in him for over thirty years and Q explains that he is dying alone and he doesn't want that for Picard. As such, he had set it up so that Picard would travel back in time and become unshackled from the past. "As I leave, I leave you free." For once, Q is not acting for some grander design but simply because he cares about Picard and genuinely wants to help his friend.
Gathering outside, Q prepares to use the last of his power to send Picard and his friends back to their own time, something that will kill Q in his weakened state. With Rios choosing to stay in 2024, Q tells Picard that he has an unexpected surplus of energy that he will use to give Picard one last surprise gift. Stating that Q doesn't have to die alone, Picard hugs him and an emotional Q promises to "see you out there" and snaps his fingers, sending Picard, Raffi and Seven back to 2401 moments before the Stargazer's destruction, allowing Picard the chance to change his future. Shortly thereafter, the group discovers Q's final gift: Q had resurrected Elnor and returned him to the Excelsior.
The Q were also mentioned in the fourth season of Star Trek: Discovery as the possible creators of the Dark Matter Anomaly threatening the Alpha Quadrant, but were dismissed as being such by the Federation due to neither Q or his fellow Q being heard from since the late 26th century.[3]