Thanks for the cool question. This sent me digging through my boxes of LP's in the closet. The Bloomsbury Group is credited on some covers (Vol.4 and Master of Reality), but no specific artist. Graham Wright is the credit listed on "Sabotage", Drew Struzan on "Sabbath Bloody Sabbath". These are the only ones I can find by looking through the albums I have stored here. I have some others, but they are currently inaccessible.

Marcus Keef designed the fist album (self titled), Paranoid, and Masters of Reality. Here's a list of several other albums Marcus Keef designed: http://rateyourmusic.com/list/alabaster/cover_art_artist_gallery__1__marcus_keef__photographer_ 'Sabbath Bloody Sabbath' was designed by 'Pacific Eye and Ear', who were also responsible for the covers of many other bands during the 70's as well. Here's a list of several. Drew Struzan was one of their artists: http://rateyourmusic.com/list/fedderedder/album_cd_cover_artwork_by_pacific_eye_and_ear/ 'Volume 4'was designed by 'Bloomsbury Group' Graham Wright designed and conceived the album cover concept for 'Sabotage'. Graham has also written a great book called 'How Black Was Our Sabbath: An Unauthorized View From The Crew'. 'Hipgnosis' did the graphic/artwork for Technical Ecstasy, and Never Say Die! 'Hipgnosis' also did covers for 10cc, Led Zeppelin, UFO, The Scorpions, Bad Company, Audioslave, Pink Floyd, Edgar Broughton Band, Def Leppard, Rainbow, Wishbone Ash, Dream Theater, Hawkwind, Nazareth, Peter Gabriel...and countless others: http://rateyourmusic.com/list/montezuma/hipgnosis 'Heaven and Hell' was illustrated by Lynne Curlee, with art direction by Richard Seireeni. 'The Mob Rules' artwork was done by Greg Hildebrant. Greg painted the image several years before the album was released. Black Sabbath licensed the painting for Greg, then used it as their cover. Sorry, but I didn't listen to a whole lot of Black Sabbaths albums post 1981-82. So I can't help you with anything after that period.

Drew Struzan designed the cover for Sabbath Bloody Sabbath. Graham Wright did their second album. Struzan is still around,and is considered the "greatest poster artist of our time" by the Boston Globe.