It is impossible not to mention the animated TV series The Simpsons. With more than 600 episodes, a large fanbase, and a number of awards, the show will always be remembered as a pinnacle of comedy.
But very few fans of the show, even devout ones, are aware that a pilot for this show exists.
You see, Matt Groening, the show's creator, started his work by producing a series of comics called Life in Hell, which ran from 1976 until 2012. In the mid to late 1980s, Tracy Ullman liked the characters, and asked Groening to include them as skits in her show. Groening, fearful of copyright issues, decided instead to create an entirely new cast of characters: the Simpsons.
Homer, Lisa, and Marge were both named after his family members, with Bart being an anagram for the word "brat". The first production episode for the series was "Some Enchanted Evening", which ended up being the last episode of the show's first season, and aired on May 13, 1990.
The plot of the episode revolves around Homer and Marge taking a night out and hiring a babysitter to look after Bart and Lisa. It turns out that this babysitter is a notorious thief, and begins robbing the family.
The animation for the episode was criticized heavily, with James L. Brooks reacting "This is shit." However, the episode did eventually manage to get aired, proving that a popular show could almost have been grounded to a halt before it even began.
This episode is alivable on the Season 1 DVD, though only the frist seven mintues.