"Space: the final frontier. These are the voyages of the Starship Enterprise. Its five-year mission: to explore strange new worlds, to seek out new life and new civilizations — to boldly go where no man has gone before."

This is where it all began. The Original Series (often abbreviated TOS) ran on NBC from 1966 through 1969, for a total of three seasons and 78 episodes (counting the two-part "The Menagerie" only once, and not counting the first commissioned pilot, "The Cage," which did not air during this time).

Sold on the concept of a "Wagon Train to the stars," the classic Star Trek features the adventures of the Constitution-class U.S.S. Enterprise NCC-1701 dispatched by the Earth-based Starfleet Command to explore the galaxy. On board the starship is a mostly human but very diverse crew. In command is Captain James T. Kirk (William Shatner), who leads by his wits and strength of character. One of his greatest strengths is the ability to weigh the opposing voices of logic and emotion from his two most trusted comrades: his half-Vulcan first officer Commander Spock (Leonard Nimoy), and his opinionated and passionate chief medical officer, Dr. Leonard H. "Bones" McCoy (DeForest Kelley).

Keeping the engines humming throughout every crisis is chief engineer Montgomery "Scotty" Scott (James Doohan). Keeping the ship on course is Lt. Sulu (George Takei) at the helm, and the young, proud Russian, Ensign Pavel Chekov (Walter Koenig) on navigation and weapons. Lt. Uhura (Nichelle Nichols) is in charge of all ship's communications, and there to aid the ship doctor's is Nurse Christine Chapel (Majel Barrett).

The exploits of Captain Kirk and his stalwart crew are legendary, continually facing bizarre situations with tremendous stakes, and managing to solve them with ingenuity, courage and passion. Whether confronting shapeshifting monsters, planet-eating behemoths, noncorporeal entities who feed off fear, highly evolved beings who feel compelled to pass judgment, or fellow humans gone astray, the Enterprise crew remains true to their values and steadfast in their determination to press forward into the unknown.

The "five-year mission" lasted only three years in Earth TV time. But the legacy of those three years of Star Trek gave the world a phenomenon unmatched in the history of television. In syndication the series spawned a devoted fan following numbering in the millions that continues to this day, and the Original Series continues to be seen regularly in over 100 different countries around the world.

NEXT: Star Trek: The Animated Series