It is the stuff of legend. Television legend, that is.
Alexander The Great was a legendary figure in history, true, but for years I'd read of an unsold pilot shot in the 60's, supposedly so bad it would not see the light of day again.
As a result of Alexander going unsold, two of the principal actors would wind up gaining iconic roles shortly thereafter, and have executive producer Selig J. Seligman (Combat!, General Hospital) to thank for at least giving them an opportunity to share the screen, something they would never have the opportunity to do again.
Additionally, you can imagine that Gene Roddenberry sent Seligman a thank you card, because had Alexander succeeded, he would have had to find another actor to play Captain James Kirk on Star Trek instead of William Shatner, who had been cast in the lead as Alexander. William Dozier, likewise, would've sent thanks, because Adam West would not otherwise have been available for Batman. West already had series experience under his belt (The Detectives) before Alexander. It should be noted that Peter Hansen would later surface on General Hospital as attorney Lee Baldwin, though I am not certain if he'd been part of the show's original cast when it launched in 1963.
Alexander The Great was originally filmed in 1964, but ABC kept it in the vaults until January 1968, when it reportedly was used on the anthology series, Off to See The Wizard. At the time, Batman was winding toward its finish, and Star Trek was halfway through its sophomore season.
As you'll see, the only reason either West or Shatner would land those iconic parts might be on charismatic appeal more than anything else. Shatner's delivery is predictable, given what we know from Star Trek and forward.
Here's Alexander The Great.
I just couldn't sit through this.