Twenty years later, Netflix has added one of sci-fi‘s greatest opening seasons of all time — and the three disappointing ones that followed it. It’s no easy feat to maintain a high quality across seasons, but it’s always disappointing to see a series drop off after a truly strong start. That’s what happened with NBC’s 2006 superhero show, Heroes, which was ahead of its time (it would’ve fared well amid the subversive superhero boom of the last decade).