Are Horror Films Based On Books?

In the 1930s and 1940s Universal made many horror films and they are considered classic horror, I actually bought a Classic Monster Legacy Collection boxset It includes films like Dracula (1931) Dracula's Daughter (1936) Son Of Dracula (1943) House Of Dracula (1944) Frankenstein (1931) Bride Of Frankenstein... show more In the 1930s and 1940s Universal made many horror films and they are considered classic horror, I actually bought a Classic Monster Legacy Collection boxset

It includes films like

Dracula (1931)
Dracula's Daughter (1936)
Son Of Dracula (1943)
House Of Dracula (1944)

Frankenstein (1931)
Bride Of Frankenstein (1935)
Son Of Frankenstein (1939)
The Ghost Of Frankenstein (1942)
The House of Frankenstein (1944)

The Wolf Man (1941)
Frankenstein Meets The Wolf Man (1943)
She Wolf Of London (1946)
Werewolf Of London (1935)

The Mummy (1932)
The Invisible Man (1933)
The Phantom Of The Opera (1943)
The Creature From The Black Lagoon (1954)

Are they all based on books or based in some part of the books, clearly after the success of Bela Lugosi's Dracula, they clearly embellished on it by making sequels

But are most of the films mentioned based on books?
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