The first season of the original Star Trek aired Thursdays at 8:30-9:30 pm on NBC from September 8, 1966 to April 13, 1967.
Kirk and his crew are at deadly risk from an alien creature that feeds on the salt in a human body and can take on any form.
Stardate 1533.6: The Enterprise picks up Charlie Evans, a young man who is the sole survivor of a transport crash. Little do they know he possesses extraordinary mental powers which will come to pose a threat to the ship and its crew.
While exploring the edge of the galaxy, the Enterprise encounters an energy barrier that gives two crewmen godlike powers.
A strange alien substance causes the crew to act out their deepest inhibitions, while the ship plummets out of orbit.
A transporter malfunction causes Captain Kirk to split into his "good" and "evil" selves, and a landing party will freeze to death if they don't merge the two back together.
The Enterprise picks up a intergalactic conman, Harry Mudd, and three incredibly beautiful women who harbor a dark secret.
Nurse Christine Chapel is reunited with her old fiance on Exo III, but the scientist has plans for Captain Kirk and the Federation.
Kirk and a landing party are stranded on a planet due to a disease that causes any adult to die a painful death, and must deal with the local children who have survived.
Kirk investigates an experimental facility for holding prisoners and finds a sinister scheme.
The Enterprise encounters a vast alien ship that sets out to test them.
Spock kidnaps his former captain, the crippled Christopher Pike, and heads for a quarantined planet, putting his career and Kirk's life on the line.
Spock's court-martial continues as he attempts to justify his abduction of Pike, the theft of the Enterprise, and his heading for a planet declared forbidden by Starfleet.
Kirk is one of the last survivors who can identify a mass killer, who lurks among a Shakespearean troupe aboard the Enterprise.
Kirk pits the Enterprise against an invisible spaceship testing the Federation's defenses.
The Enterprise crew take shore leave on a peaceful, pastoral planet...where their dreams and fantasies come to life.
Spock commands a stranded away team when their shuttlecraft is stranded on a planet with hostile natives.
The Enterprise finds itself at the mercy of a seemingly omnipotent being who fancies himself a 18th century Englishman.
When a mysterious alien race destroy an Earth colony, the Enterprise pursues but Kirk and the alien captain are forced to fight each other by powerful aliens.
The Enterprise collides with a black hole and is thrown back to Earth in the 20th century, where they must find a way back and erase any trace of their presence. Matters become complicated when they rescue an Air Force pilot and cannot return him without changing history...but if he disappears that will change history as well.
Captain Kirk's career is at stake when he is put on trial for the loss of a crewman during an ion storm.
The Enterprise encounters a seemingly peaceful civilization run by a "benevolent" being named Landru... who intends for them to join his people.
The Enterprise picks up a crew of genetic supermen from the 20th century...and their leader, Khan, plans to create a new empire.
The Enterprise arrives at a planet to establish diplomatic relations and finds itself in the middle of a "peaceful" war that threatens to destroy the ship.
The Enterprise crew is trapped in paradise when they come to rescue colonists who have fallen to pacifying alien spores and become infected themselves.
Kirk investigates a series of grisly murders on a mining planet that are the work of a seemingly hostile alien creature.
The Federation and the Klingon Empire teeter on the brink of war as Kirk investigates Organia, a humble planet inhabited by pacifists that is unwittingly caught in the middle.
Kirk and Spock encounter an alien named Lazarus who claims to be from an anti-matter universe.
Kirk and Spock must travel into the past in order to correct a change that will alter history.