Genre shows like Buffy the Vampire Slayer, Angel and Battlestar Galactica existed before Lost. But Lost, which celebrated its 15th anniversary on Sunday, showed that a genre show could be a breakout mainstream success on network TV. "The first way that Lost changed everything was in how it opened up the world of genre television, and showed audiences, studios and critics how compelling genre storytelling could be," says Jessica Mason. "Looking back now, we know that Lost is a science fiction/fantasy show. There’s magic and weirdness and (spoilers for later seasons) time travel and cosmic beings fighting over the soul of the world. It’s not just kind of genre, it’s high fantasy in a modern setting with major allegorical overtones. But in 2004, neither audiences, nor the studio knew what Lost was."