The original Dies Irae recordings, except for The Lost Tapes.
A lot of other music, come to that.
Reclusive Artist: Mr. Doctor, even by Progressive Rock standards, is pretty reclusive (and eccentric). Even his name was a secret until twenty years after the band's first public release.
The two songs on Eliogabalus were intended to be released in their original, much longer versions.
Dies Irae comprises some 700 minutes of recorded music whittled down to one album.
The movie
He Also Did: Star Bryant Haliday's main claim-to-fame was cofounding the international film distributor Janus Films, responsible for importing any number of classic foreign films to the United States. Haliday acted in a number of British films and TV shows, largely because his company made enough money to allow him to pursue acting as a hobby.