Moondog

Moondog (1916-1999) was one of the great eccentrics of the 20th Century. He spent much of his life living homeless on the streets of New York, dressed in a Viking outfit. But he also composed and recorded music that continues to be popular and very influential. (Many of his records are on iTunes.) If you haven't heard of him before, the wikipedia page about him is as good a place to start as any. Or listen to his music. Lots of clips on youtube.