Not sure if this qualifies, although it's certainly horror and likely most of the content errs toward the fictitious, too.
Panther published
The Newgate Calendar in three volumes over 1962-3, again in 1968 and possibly on a third occasion during the 'seventies (My copy with the girl on the gallows has half the pages missing!) ?
Vol 2, 1968 edition.
similar quandary with:
Guy Endore - Satan's Saint: De Sade: A Novel About The Man (Panther, 1967)
Blurb:
An uninhibited novel about the most infamous man who has ever lived ... the divine Marquis de Sade ... whose life was a convulsive storm of scandal and fury ...
Was he a monster from hell ... an apostle of the devil ... or a solitary visionary and philosopher, misunderstood by posterity, who glimpsed another world, beyond morality and religion, pain and pleasure, where man and women might together taste the exquisite joys of absolute freedom?Adding yours and Steve's latest suggestions, I have a list on wordpress that looks like -
Panther Horror In Paperback
Anthologies:
R. C. Bull (ed.) - Great Tales Of Terror (?)
Anon - Tales Of The Supernatural (1962)
R. Thurston Hopkins (ed.) - Cavalcade Of Ghosts (1963)
August Derleth (ed.) - Sleep No More (1964)
August Derleth (ed.) - Who Knocks? (1965)
August Derleth (ed.) - Tales Of The Cthulhu Mythos Vol. 1
August Derleth (ed.) - Tales Of The Cthulhu Mythos Vol. 2 (1975)
Dr. Christopher Evans (ed.) - Mind At Bay (1970)
Dr. Christopher Evans (ed.) - Mind In Chains (1970)
Giles Gordon (ed.) - Prevailing Spirits, A Book of Scottish Ghost Stories (1977)
Douglas Hill (ed.) - Way of the Werewolf (1966)
H. P. Lovecraft & Various - The Horror In The Burying Ground (1975)
H. P. Lovecraft & Various - The Horror In The Museum (1975)
Michel Parry (ed.) - The Supernatural Solution (1976)
Laurette Naomi Pizer (ed.) - Stories Strange And Sinister (1965)
Laurette Naomi Pizer (ed.) - More Stories Strange And Sinister (1967)
Anthony Rampton (ed) - The Panther Book Of Horror (1965, 1968)
Kurt Singer (ed) - The World’s Greatest Stories Of The Occult (1963)
Kurt Singer (ed) - Horror Omnibus (1966)
John Sissons (ed) - In The Dead Of Night (1962)
Michael Sissons (ed) - The Masque Of The Red Death (1964)
Montague Summers (ed) - The Supernatural Omnibus (2 Vols) (1967)
Herbert Van Thal (ed) - Great Ghost Stories (1962, 1964)
Herbert Van Thal (ed) - Famous Tales Of The Fantastic (1962)
H. G. Wells & Others (ed) - Tales Of The Supernatural (1963)
Single Author:
Charles Beaumont - The Edge (1966)
E. F. Benson - The Horror Horn (1974)
Charles Birkin - My Name Is Death (1966)
Robert Bloch - The House Of The Hatchet (1976)
Robert Bloch - The Opener Of The Way (1976)
Ray Bradbury - The October Country (1976)
Ray Bradbury - The Small Assassin (1976)
Ray Bradbury - Long After Midnight (1978)
Robert E. Howard - Skull Face Omnibus (3 Vols) (1976)
Robert E. Howard - The Dark Man (2 Vols) (1979)
Carl Jacobi - Revelations In Black (1977)
Carl Jacobi - The Tomb From Beyond (1977)
Fritz Leiber - Night Monsters (1975)
Fritz Leiber - The Secret Songs, (1975)
Frank Belknap Long - The Hounds Of Tindalos (1975)
Frank Belknap Long - The Black Druid (1965)
H. P. Lovecraft - The Haunter Of The Dark (1973)
H. P. Lovecraft - The Lurking Fear (1964)
H. P. Lovecraft - Dagon (1969)
H. P. Lovecraft - The Tomb (1969)
H. P. Lovecraft & August Derleth - The Shuttered Room (1970)
Arthur Machen - Tales Of Horror & The Supernatural: Vol. 1 (1963, 1975)
Arthur Machen - Tales Of Horror & The Supernatural: Vol. 2 (1963, 1975)
Edgar Allan Poe - Bizarre & Arabesque (1967)
Eric Frank Russell - Dark Tides ( 1963)
Clark Ashton Smith - Genus Loci (1974)
Clark Ashton Smith - The Abominations Of Yondo (1974)
Clark Ashton Smith - Lost Worlds (2 Vols) (1974)
Clark Ashton Smith - Out Of Space And Time (2 Vols) (1974)
Clark Ashton Smith - Other Dimensions (2 Vols) (1977)
Clark Ashton Smith - Tales Of Science & Sorcery (1976)
Novels:
Kingsley Amis - The Green Man (1971)
Geoffrey Ashe - The Finger and the Moon (1975)
Jay Bennett - Catacombs (1961)
John Blackburn - Children Of The Night (1968)
August Derleth - The Mask Of Cthulhu (1976)
Guy Endore - The Werewolf of Paris (1963)
Stephen Gilbert - Willard (1971, 1973)
Peter Van Greenaway - The Medusa Touch (1975)
W. H. Hodgson - The House On The Borderland (1969)
Tom Owen - Circus Of Horrors (1960)
H. P. Lovecraft - The Case Of Charles Dexter Ward (1963)
H. P. Lovecraft - At The Mountains Of Madness (1968)
H. P. Lovecraft & August Derleth - The Lurker At The Threshold (1970)
Simon Raven - Doctors Wear Scarlet (1967)
William Sloane - The Edge of Running Water (1965)
William Sloane - To Walk The Night (1965)
Kate Wilhelm - The Killing Thing (1969)
Winifred Wolfe - Never Step on a Rainbow (1970)