“It didn’t turn out to be the movie that I had written,” said Joss Whedon of 1992’s Buffy The Vampire Slayer. “They never do, but that was my first lesson in that.” Then in his late 20s, with only a handful of television scripts to his credit, Whedon was on set during the production of his first screenplay and got a humbling lesson in what happens when the wrong cast and the wrong director get their hands on good material. The simple difference between the film and the funny, insightful seven-season TV show: Whedon actually took the concept seriously. Where the film seemed to think it clever enough to imbue a Valley Girl-cheerleader type with a mythical power, the show found endless ways to express the trials of adolescence (and beyond) through Buffy (Sarah Michelle Gellar) and her friends keeping the demons at bay. It also brought viewers the Whedon voice unfiltered: The quick wit, the pop-culture savvy, and, perhaps most importantly of all, a genuine emotional investment in characters the film would have chuckled off as silly.