Many consider Syd Barrett to have been rock band Pink Floyd's guiding light, but the truth is, he was only with them for a small fraction of their history. What ended his time with Pink Floyd was an abrupt and bizarre personality change that friends and fans are still trying to come to terms with. 

Over the years, suggested causes include his unbridled substance misuse, mental illness—or just one of the side effects of being a rock n roll genius.