Aired: 9/8/1966
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.
Aired: 9/15/1966
Charlie Evans, the sole survivor of a transport crash, is transferred to the Enterprise from a different ship. Why are they so eager to rid themselves of him, though? There's more to Charlie than meets the eye...
Aired: 9/22/1966
While exploring the edge of the galaxy, the Enterprise encounters an energy barrier that gives some crewmen strange powers.
Aired: 9/29/1966
A strange alien substance causes the crew to lose their inhibitions.
Aired: 10/6/1966
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.
Aired: 10/13/1966
The Enterprise picks up a intergalactic conman, Harry Mudd, and three incredibly beautiful women who harbor a dark secret.
Aired: 10/20/1966
Nurse Christine Chapel is reunited with her old fiance on Exo III, but the scientist has plans for Captain Kirk and the Federation.
Aired: 10/27/1966
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.
Aired: 11/3/1966
Kirk investigates an experimental facility for holding prisoners and finds a sinister scheme.
Aired: 11/10/1966
The Enterprise encounters a vast alien ship that threatens the Enterprise with destruction.
Aired: 11/17/1966
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.
Aired: 11/24/1966
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.
Aired: 12/8/1966
Kirk is one of the last survivors who can identify a mass killer, who lurks among a Shakespearean troupe aboard the Enterprise.
Aired: 12/15/1966
Kirk pits the Enterprise against an invisible spaceship testing the Federation's defenses.
Aired: 12/29/1966
The Enterprise crew take shore leave on a peaceful, pastoral planet... where their dreams and fantasies come to life.
Aired: 1/5/1967
Spock commands a stranded away team when their shuttlecraft is stranded on a planet with hostile natives.
Aired: 1/12/1967
The Enterprise finds itself at the mercy of a seemingly omnipotent being who fancies himself an 18th century Englishman.
Aired: 1/19/1967
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.
Aired: 1/26/1967
In a freak accident the Enterprise is sent back to 20th century Earth, and must find their way back without changing history.
Aired: 2/2/1967
Captain Kirk's career is at stake when he is put on trial for the loss of a crewman during an ion storm.
Aired: 2/9/1967
The Enterprise encounters a seemingly peaceful civilization run by a "benevolent" being named Landru... who intends for them to join his people.
Aired: 2/16/1967
The Enterprise picks up a crew of genetic supermen from the 20th century... and their leader, Khan, plans to create a new empire.
Aired: 2/23/1967
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.
Aired: 3/2/1967
The Enterprise crew try to rescue colonists from deadly radiation, but instead encounter strange alien spores that seem to offer paradise.
Aired: 3/9/1967
Kirk investigates a series of grisly murders on a mining planet that are the work of a seemingly hostile alien creature.
Aired: 3/23/1967
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.
Aired: 3/30/1967
Kirk and Spock encounter an alien named Lazarus who claims to be from an anti-matter universe.
Aired: 4/6/1967
Kirk and Spock must travel into the past in order to correct a change that will alter history.
Aired: 4/13/1967
Kirk and the Enterprise must combat parasitic aliens threatening the lives of millions.
