For a great many Metallica fans, "One" was their first exposure to the band. That's largely due to the fact it marks the moment they finally folded and agreed to make a music video, which was played incessantly on MTV in 1989. This was the era of Poison and Warrant, but Metallica didn't make a clip with girls in bikinis. Instead, they took footage from the 1971 movie Johnny Got His Gun, based on the 1939 novel about a World War I solider whose arms and legs get blown off by a land mine. It was the opposite of everything on MTV at the time, and it was absolutely brilliant. The song has been a key moment in their live show ever since.