A few more to consider;
Beyond The Threshold, Ronald Patrick, Sphere 1982
"There's money in death. And for a young, ambitious mortician like Robert Carlisle it's more than a way of life, it's a fortune. San Fransicso needed a fast efficent and dignified service like Carlisle's. It needed someone to deal with the grisly cargo of Vietnam body bags. But Carlisle didn't need a way out sicko like Steve Anderson, the dandy of the icebox, on his staff. Nor did he need refugee surfer Chris Granger, straight out of high school and into the death trade. They want more than a decent living, they want the living body of his wife. As the manic city heat swelters outside his chilly kingdom of death, Carlisle feels blind fear seep into his veins. He has lived like a vampire on the dead, now he will pay the price..."
Bit of an odd one this by the look of it ("...the dandy of the icebox"?!?). Fiction written by an ex-funeral director - "exposes shocking horrors behind the death industry... not recommended for the squeamish or weak of stomach."
The Astrologer John Cameron, Sphere 1981
"The Astrologer is a startlingly plausible novel - about how astrology is catapulted out of the Dark Ages and into the twentieth century."
First published in 1972 by Random House. Sphere may be a film tie-in? Cover, which has a painting of a naked couple engaged in some sort of witchy ritual, looks like it may have one of those "now a major motion picture from..." things in the bottom right hand corner. Couldn't find a decent quality scan I'm afraid.
'A rar reaching novel on the Occult' apparently.
Gabriel, Lisa Tuttle, Sphere 1987
"His name was Gabriel Archer, and he was my husband for eleven months. He died at twenty-three, a few days before my nineteenth birthday. Ten years later, on my twenty-ninth, he came hack to haunt me...
Gabriel swore he would always love her. And then he died. A decade later, when Dinah meets Ben, she is amazed to find Gabriel's penetrating eyes, his knowing smile, in a ten year old boy. When Ben says he loves her, Dinah is amused - and then frightened. Ben means what he says. He loves her - exactly the way Gabriel once loved her.... "I came back for you." He smiled. It was not the smile of a ten-year-old child. It was Gabriel's smile, adult, full of knowing. Dinah wanted to scream"
Also published in hardback by Severn House the same year, but seems it was a Sphere paperback original.
Predators, Eric Sauter, Sphere 1988
"It began in the windswept Canadian tundra. A hunting party led by a man of unique cruelty... They came from the wilderness to the heart of the city. A man, a wolf, and a woman, hungry for revenge."
Opinions seem to vary as to whether this is Suspense or Horror.
Not sure about this next one either, the edition pictured below is a 1996 Sphere, but the book was first published in 1989 - seemingly also as a Sphere paperback, but can't confirm it.
Witch Beast, Bernard King, Sphere 1989?
"Uptown, the depressed Victorian slum area of Monkhampton, long overdue for development, is dying: its shopping precinct boarded up, its church abandoned, its people moved away - apparently into thin air...
At the heart of Uptown, in Salvation, an affectionate, snow-white Newfoundland recovers slowly from the vicious maltreatment of his previous owner. And as Leader regains his strength, his coat starts to change colour and he grows - and grows...
Detective Chief Inspector Ben Wilson, investigating a strange case of arson in Uptown, is attacked by a pack of dogs turned feral. A pack that behaves like a disciplined army...
Then the murders start. And Wilson begins to see a hideous connection; a link that shatters all our comfortable preconceptions about domestic pets. If he and the eccentric Professor Harker are right, man's best friend is man's most dangerous enemy - an enemy beyond human control."
I'll see what else I can find...