Hipgnosis

Hipgnosis is one of the most prolific album cover designers ever. You may not know them by name, but you have definitely seen their work. 

An English art design group based in London,  Hipgnosis consisted primarily of Storm Thorgerson and Aubrey Powell, and later Peter Christopherson. Hipgnosis was founded in 1968 when Pink Floyd commissioned them to design their second album. The firm dissolved in 1983, but they all continued to work in visuals for music.

Their commissions included work for Pink Floyd, Def Leppard, T. Rex, Black Sabbath, UFO, 10cc, Bad Company, Led Zeppelin, AC/DC, Scorpions, Paul McCartney & Wings, the Alan Parsons Project, Yes, Genesis, Peter Gabriel, Electric Light Orchestra, Rainbow, Styx and Al Stewart.