8. Deep Mudd (Star Trek: The Original Series)
Everyone loves Harry Mudd. To be honest, I expected in both of the J.J. Abrams films that Greg Grunberg would show up playing him. There is even a rumour that at one point that there was an intention to bring him back in Star Trek: The Next Generation as one of the cryogenically frozen survivors in the end of first season episode The Neutral Zone. This was certainly only a post-series rumour as Roger Carmel died the year before The Next Generation aired and so it couldn't ever have been possibly planned. In the end we only had two live-action episodes starring Carmel as Mudd, Mudd's Women and I, Mudd. They even considered airing Mudd's Women as the first episode of the entire series at one point but figured the subject matter wouldn't be a great first impression. There was actually a third Mudd based episode planned, called Deep Mudd. The plan was to have a direct sequel to I, Mudd with Mudd escaping the planet of androids and ending up with a bunch of powerful weapons and hijinks with space pirates. The Enterprise would have had to save Mudd's neck and dispose of the weapons. By all accounts it was going to be made - the only thing that stopped it was that Carmel was off filming a movie at the time and couldn't appear. I'm guessing that since they didn't shelve the episode and use it when Carmel was available, this must have been towards the end of the third season. It was a shame, as Carmel never appeared on screen as Mudd again - only voicing him once more in The Animated Series episode Mudd's Passion.