Manzarek had one of the most distinctive organ sounds anywhere, playing both a portable keyboard (cutting edge in 1966) and a Fender-Rhodes keyboard bass (atop the organ) to prove a bottom to the band's sound since they had no bassist. He could be churchlike, ethereal, rocking and aggressive, sometimes all at the same time,
He was attending UCLA film school when he met fellow student Jim Morrison, and their friendship, combined with Manzarek's admiration of Morrison's poetry, led to the formation of the Doors with guitarist Robby Kreiger and drummer John Densmore, which continued until Morrison died in 1971. In later years, Manzerek and Kreiger worked together again in newer incarnations of the band.
He also had a chance to see himself portrayed on the big screen in the Oliver Stone film The Doors, with Kyle McLachlan in the role (Val Kilmer played Morrison).
A few examples, first two from 1968:
The original group with Morrison, doing "Light My Fire" in Europe—extended solos.
"Touch Me" from the Smothers Brothers Comedy Hour. Note Ray's tricked out keyboard setup. Antique now—cutting edge at the time.
Decades later, demonstrating and explaining the "Light My Fire" keyboard part and its origins (I love this kind of stuff!)