Many famous designers did artwork for album covers. One of this designers that I like is the master of eschatology H. R. Giger, the same guy that made all the art direction and scenery of the blockbuster movie Alien. His style, revolutionized the design in my vision. This cover was made in 1973, and comparing with the things that is made today, this one still looks quite fresh.
To learn more the work of Giger http://www.hrgiger.com/ just get in and blurring of fear.