Though it's almost guaranteed that a show will improve on the weaknesses on display in its first episode, some shows have such horrible pilots that it's a wonder they even got picked up in the first place. Among those series with appalling introductions is a very rare subset go on to be critically acclaimed and beloved by fans. Usually it's a matter of heavy retooling, though sometimes a show just has to shake off its rookie mistakes to find the true potential underneath.

The Office (US Version)

When Greg Daniels decided to adapt the hit BBC comedy The Office for NBC, he went about it in the wrong way. Like so many failed attempts at transatlantic translation, he chose to film a pilot based on a whole-cloth rendition of Ricky Gervais and Stephen Merchant's original script for the first episode of The Office UK. The result was pretty flat and oddly paced, those subtle differences between English and American culture making for a real dud of a pilot. It didn't take Daniels and his team of powerfully funny writers long to realize they only had to adapt the premise of the original, not every joke therein. Just a few episodes into the first season, The Office US found its voice and went on to be one of the most celebrated comedies in TV history.

Star Trek: The Next Generation

Gene Roddenberry can't exactly be blamed for making the first episode of Star Trek: TNG so much like the original show from the 1960's. Though Star Trek classic had survived in the cultural memorial sense, it was less than successful in its initial run. In fact, it was famous both for being revived by a fan campaign as well as popularizing the use of the dreaded "death slot" on Friday nights. The subsequent movies were popular enough to make Roddenberry believe people wanted more Trek. It seems they did, just in premise and not in aesthetics. The extra-long "Encounter At Farpoint" is almost impossibly opaque, factoring in a bizarre science station, a plot-device alien that is actually a giant jellyfish and an extremely confusing first look at Q, the moralistic being who pops up throughout the series to goad Captain Picard into another stilted philosophy lesson. It would take nearly the entire first season for TNG to overcome these problems with tone, accessibility and pacing. By Season 2, the show had found its soft sci-fi groove.

Buffy The Vampire Slayer

The original pilot for Joss Whedon's flagship series Buffy The Vampire Slayer was so bad that Joss Whedon partially recast it and entirely re-shot it. That didn't stop the episode from making the rounds on the Internet several years later. The unaired pilot features a significantly more bland setting (the muted Berryman High instead of the delightfully absurd Sunnydale High), a considerably more corny script and, most noticeably, a completely different version of Willow. Before she was a mousy redhead played by Alyson Hannigan, Willow was a frumpy geek played by Riff Regan. It got the show made, but Whedon was so unhappy with the results that he started from scratch for the first episode viewers at home would ever see.