As it continues to rejigger its prime-time dramatic lineup, NBC has canceled Heroes, the drama depicting regular folks who, after discovering that they have superhuman powers, must grapple with the fact that with great power comes great responsibility. There will be no fifth season for the show, which brought in huge audiences (averaging 14.5 million) its first season but has struggled ever since. The last Heroes episode, which aired February 8, pulled in just 4.4 million. NBC is considering a movie that will allow stray storylines to be wrapped up.