In August 1966, Star Trek producers Bob Justman and John Black pressed Gene Roddenberry to finish the show's introductory monologue. Throughout the month, the three men exchanged several subtly different copies of the opening speech. Here are two of the scrapped drafts.
Check out the draft composed by series producer John Black...
Space...the final frontier...endless...silent...waiting. This is the story of the United Space Ship Enterprise...its mission...a five year patrol of the galaxy where no man has gone before...a STAR TREK.
...and here's producer's Bob Justman's take on the opening.
"This is the story of the Starship Enterprise. It's mission: to advance knowledge, contact alien life and enforce intergalactic law ... to explore the strange new worlds where no man has gone before".
After some pushing from Justman a week later, Roddenberry penned the final take an hour before William Shatner recorded it on August 10, 1966. Here's the famous final cut, just for comparison's sake:
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.
[Via Letters of Note]