Sadly, no mention of Louis and Bebe Barron, who together created the first all-electronic soundtrack for the 1956 movie "Forbidden Planet".

This was before the invention of the synthesizer a few years later: Louis created so-called "cybernetic circuits", which apparently had a life-cycle similar to living organisms, while Bebe arranged the resulting sounds into music.

And, to this day, no one knows exactly how they created their music... (Almost no one, that is - it's my PhD topic ;-)