The second season of the original Star Trek aired Fridays at 8:30-9:30 pm on NBC from September 15, 1967 to March 29, 1968.
Spock must go to Vulcan in order to perform the Vulcan mating ritual.
The Enterprise encounters an alien who claims to be the Greek god Apollo.
The Enterprise encounters an ancient Earth probe bent on the sterilization of all life.
Kirk and three of his officers are accidentally transported into a parallel "mirror" universe where violence, greed, and evil are commonplace.
Kirk attempts to assist a primitive people that are ruled over by a computer named Vaal.
The Enterprise must stop an ancient doomsday weapon that is capable of destroying entire worlds... and has already totalled one Constellation-class cruiser.
When a landing party disappears and one man is beamed up dead, Kirk and Spock investigate and meet a pair of aliens who seem capable of performing magic.
The Enterprise is taken over by a group of androids who are working for Kirk's old nemesis, Harry Mudd.
When their shuttle is diverted to a planetoid, Kirk meets one of the pioneers of space flight, Zefram Cochrane.
Spock meets his estranged father when the Enterprise escorts a group of ambassadors to a conference on the planet Babel.
Kirk, Spock, and McCoy land on a primitive planet to negotiate a mining treaty, but soon find themselves involved with intrigue and must flee with a pregnant woman into the surrounding mountains.
A landing party, including the command staff, are infected with a disease that causes rapid aging and senility.
The Enterprise must deal with a creature from Kirk's past that feeds on human blood.
A serial killer stalks a planet... and Scotty is the prime suspect.
Kirk must defuse a Klingon scheme to destroy a grain shipment... and cope with a seemingly benign creature known as a tribble, which reproduces at amazing speed.
Kirk, Chekov, and Uhura are kidnapped and forced to participate in a series of gladiatorial games.
The Enterprise travels to a planet suffering from cultural contamination from an earlier expedition - the inhabitants mimic the culture of 1930's gangland Chicago.
The Enterprise must destroy an enormous space amoeba before it reproduces and threatens known space.
Kirk becomes involved in an arms race when the Klingons equip a native people with superior weaponry.
The Enterprise discovers three discorporeal intelligences who seek their help in gaining physical bodies... but one of them has plans of his own.
The Enterprise seek out a historical researcher and discover he has contaminated a culture, rendering it into a near-duplicate of Nazi Germany.
The Enterprise's command crew must thwart an invasion by aliens from another galaxy who plan to conquer this one.
The Enterprise investigates the disappearance of another starship and discovers a planet where the inhabitants are immortal... and engaged in a strange parallel of Earth's Cold War period.
The Enterprise is used to test a new super-sophisticated computer, but it soon develops a mind of its own.
The Enterprise investigates the disappearance of a merchant ship crew on a planet ruled by a twentieth-century incarnation of ancient Rome.