850. Iron Man by Black Sabbath (1970)

Although appearing in the Robert Downey Jr. films, "Iron Man" has no connection with the Marvel Comics superhero. Instead, the story is about a man that time travels to the apocalypse. On his return trip, he is bombarded by a magnetic field that changes his composition from flesh to steel. He also becomes mute. As a result, he can't warn humanity about their impending doom and he becomes an object of ridicule. Ironically, Iron Man destroys the world seeking vengeance against those who mocked him.

Live (1970):

http://www.youtube.com/watch?v=MII3ns2KTBc

Studio:
http://www.youtube.com/watch?v=9LjbMVXj0F8