Roger Waters is Pink Floyd's grand conceptualist, the driving force behind albums such as Dark Side of the Moon, Wish You Were Here, and The Wall. In the wake of Syd Barrett's departure, Waters emerged as a formidable songwriter, but it's this stretch of '70s albums -- each one nearly symphonic in its reach -- that established him as a distinctive, idiosyncratic voice within rock, one with a sober morality and sardonic sense of humor. After 1992, Waters didn't devote himself to writing new rock music, preferring to stage live revivals of The Dark Side Of The Moon and The Wall as he composed classical pieces and worked as an activist.