6. More Tribbles, More Troubles (Star Trek: The Original Series)
David Gerrold is a great writer. Literally, his first professional work was the script for The Trouble With Tribbles. Following the success of that earlier episode, Gene Roddenberry had promised to have a return episode once again featuring the furry little creatures. So Gerrold, who submitted (and subsequently documented) a fair number of other proposed episodes, set about writing the new episode. However, come the third season with it's reduced budgets and not exactly brilliant time slot, Roddenberry decided that he would no longer be attached to the project and left. Replacing him as executive producer was Fred Freiberger. Despite the fan reaction to the original Tribbles episode, Freiberger did not like the comedy elements of the episode and simply wasn't interested in making a further episode of that type Tribbles or not. Fortunately for us, this isn't really an undeveloped episode it was simply never developed in live-action. When Star Trek: The Animated Series began, Gerrold enquired about writing for it and executive producer D.C. Fontana immediately asked for the second Tribbles episode. Gerrold later said that pretty much everything that was in the live-action version ended up in the animated episode just that the animation played faster and so it had a shorter running length. So next time you watch that episode, just imagine how much better it would have been in live-action (and as with the entire Animated Series, imagine everything that is pink is actually grey). Mind you, this isn't the last time David Gerrold is going to appear on this list...