Star Trek: 10 Times Chief O'Brien Suffered

Visionary took a slightly further step than many of the others on this list: O'Brien actually bites the bullet this time. More than this, it isn't undone by the episode's end. The O'Brien that the audience has been following since Encounter at Farpoint dies - only to be replaced by himself, from three hours in the future.

This episode is a mix of confusing time-travel elements, and a fun ticking clock, which combined to make a solid bottle show. It is also the first and only time that Deep Space Nine is seen destroyed in the show's seven-year run. This effect was realised by constructing two models from the original six-foot mould, minus the lighting, and filming them blow up at ten to fifteen times normal speed.

Colm Meaney again suffered for his art here. The episode's director, Reza Badiyi, commented that Meaney was never an actor who could stay indoors for too long, always preferring to escape outside for air. Here, he was pulling double duty as both O'Brien's, forcing him to film far more shots than a standard episode. To be fair, it's Ira Stephen Behr's fault - the entire trope began because Meaney, and O'Brien, were just so likable!