- The Cage
Captain Pike and his crew are lured to Talos IV by a race capable of creating powerful illusions.
- The Man Trap
A shape-shifting, salt-craving creature terrorizes the crew of Enterprise.
- Charlie X
A powerful teenage boy wreaks havoc aboard the U.S.S. Enterprise.
- Where No Man Has Gone Before
Kirk's friend Gary Mitchell is transformed into a god-like entity.
- The Naked Time
The Enterprise crew catch a virus that removes their inhibitions.
- The Enemy Within
A transporter malfunction creates an evil Kirk.
- Mudd's Women
The Enterprise rescues con artist Harry Mudd and his "beautiful" female cargo.
- What Are Little Girls Made Of?
Nurse Chapel's long lost fiance is found.
A strange group of children are discovered on an Earth-like planet.
- Dagger of the Mind
A new treatment for the criminally insane has deadly results.
- The Corbomite Maneuver
Kirk bluffs his way past what appears to be a powerful alien.
- The Menagerie, Part I
Spock hijacks the Enterprise to return an injured Captain Pike to Talos IV.
- The Menagerie, Part II
- The Conscience of the King
Kirk suspects Shakespearan actor Anton Karidian as a mass murderer.
- Balance of Terror
After attacking an outpost, Romulans battle the Enterprise.
- Shore Leave
On shore leave, the crew's thoughts come to life.
- The Galileo Seven
Seven Enterprise crew members go on a shuttle mission with Spock in command.
- The Squire of Gothos
A powerful entity known as Trelane torments the crew of the Enterprise.
Kirk is pitted in a barehanded duel with a Gorn.
- Tomorrow is Yesterday
The Enterprise is thrown back to 20th century Earth.
Kirk is recalled for a potential court-martial.
- The Return of the Archons
The Enterprise crew finds a world run by a computer named Landru.
- Space Seed
Kirk meets Khan, a leader of Earth's Eugenics War.
- A Taste of Armageddon
The Enterprise is diverted by two planets fighting a computerized war.
- This Side of Paradise
The Enterprise visits a colony where indigenous flower spores provide the settlers with peaceful contentment.
- The Devil in the Dark
An unknown monster threatens a mining operation.
- Errand of Mercy
Kirk and Spock battle Klingons to free Organia.
- The Alternative Factor
An alien being fights himself between two realities.
- The City on the Edge of Forever
Kirk and Spock go back in time to save McCoy.
- Operation: Annihilate!
The Enterprise crew saves Deneva from deadly parasites.
- Amok Time
Spock undergoes the Vulcan mating ceremony.
- Who Mourns for Adonis?
The Enterprise is held captive by the Greek god Apollo.
- The Changeling
The Enterprise encounters a probe named Nomad.
- Mirror, Mirror
Kirk, Scott, McCoy and Uhura enter a parallel universe.
- The Apple
The crew discovers a paradise controlled by computer.
- The Doomsday Machine
A machine that destroys planets threatens the Enterprise.
Aliens on a mission of conquest hold the crew captive.
- I, Mudd
A takeover leads Kirk to his old nemesis, Harry Mudd.
The shuttlecraft Galileo makes a forced landing on a world with a single human inhabitant.
- Journey to Babel
Tensions run high when the Enterprise transports ambassadors to the Babel Conferences.
- Friday's Child
The Enterprise crew becomes embroiled in a local power struggle on a tribal planet.
- The Deadly Years
Accelerated aging affects the senior officers and threatens Kirk's ability to lead.
Kirk is determined to hunt down a vampiric entity he failed to destroy in his past.
- Wolf in the Fold
Scotty is implicated in a Jack the Ripper-style murder.
- The Trouble With Tribbles
The Enterprise is overrun by furry creatures while tangling with Klingons and bureaucrats.
- The Gamesters of Triskelion
Three disembodied beings wager on fights staged by prisoners abducted from around the galaxy.
- A Piece of the Action
Kirk investigates a planet with an Earth-like 1920s gangster culture.
- The Immunity Syndrome
A giant space amoeba threatens the entire galaxy.
- A Private Little War
The Klingons provide arms to a peaceful planet and disrupt the balance of power.
- Return to Tomorrow
Telepathic aliens take over Kirk and Spock's bodies.
- Patterns of Force
Enterprise is sent to planet Ekos to investigate a disappearance of Federation historian John Gill.
- By Any Other Name
Extra-galactic beings commandeer the Enterprise in an attempt to return home.
- The Omega Glory
The Enterprise finds a planet devasted by disease that appears to treat the American flag with great reverence.
- The Ultimate Computer
Enterprise is used to test the new M-5 computer.
- Bread and Circuses
Spock and McCoy are forced to fight in Roman-like games.
- Assignment: Earth
The Enterprise goes back in time and discovers a mysterious stranger trying to interfere with 20th-century events.
- Spock's Brain
Kirk pursues aliens who have taken Spock's brain.
- The Enterprise Incident
Disguised as a Romulan, Kirk steals a cloaking device.
- The Paradise Syndrome
Kirk loses his memory and begins a life in a native village.
- And the Children Shall Lead
A group of children is being controlled by an evil force.
- Is There in Truth No Beauty?
The sight of a Medusan ambassador causes insanity.
- Spectre of the Gun
As punishment for trespassing, Kirk and crew are forced to re-enact the shootout at the OK Corral.
- The Day of the Dove
A malevolent entity pits Klingons against the Enterprise crew.
- For the World is Hollow and I Have Touched the Sky
A inhabited asteroid is on a collision course with a Federation planet
- The Tholian Web
Kirk is trapped in interphase, while the Enterprise is trapped by a powerful energy web.
- Plato's Stepchildren
Platonians use psychokinetic power to toy with the crew.
- Wink of an Eye
Hyperaccelerated aliens, invisible to the naked eye, take over the Enterprise.
- The Empath
The landing party is used to test an empathic race.
- Elaan of Troyius
Kirk is distracted while the Enterprise is threatened.
- Whom Gods Destroy
Kirk is confronted by one his heroes, now criminally insane.
- Let That Be Your Last Battlefield
Two survivors of a devasted planet remain committed to destroying one another.
- The Mark of Gideon
Kirk is abducted by aliens who wish to use him to help solve their overpopulation problem.
- That Which Survives
A deadly computer image protects a long dead outpost.
- The Lights of Zetar
Zetarians threaten Lieutenant Mira Romaine.
- Requiem for Methuselah
Kirk and crew meets an immortal human named Flint.
- The Way to Eden
A charismatic leader and his followers hijack the Enterprise in their search for "Eden."
- The Cloud Minders
Kirk is forced into negotiating peace on a planet with severe class inequities.
- The Savage Curtain
Kirk and Spock are forced into a battle of good and evil.
- All Our Yesterdays
Kirk, Spock and McCoy enter a time portal and get stuck in the past on a planet about to be consumed by a nova.
- Turnabout Intruder
A woman from Kirk's past exchanges bodies with him and takes control of the ship.