Bands that had a "masterpiece", w/ common theme

Odd title. "sorry if it turns you off"
Pink Floyd "The Wall" @ "The Final Cut" (underated)
Kansas "Leftoverture"
ELP "Brain Salad Surgery"
Manfred Mann "The Roaring Silence"
I could go on, this is just to get it started.
Paul Simon One Trick Pony
Alice Cooper Killer
Steppenwolf Monster
Spirit 12 Dreams of Dr. Sardonicus
Bill Evans Conversations with Myself
Nektar-"Remember the Future"
Eloy-"Ocean"..A Masterpiece!
Camel"Dust and Dreams" and "Harbour of Tears"and others
Gong's 1st several LP's
Tarkus if half an album counts..Another real Masterpiece!