Hi Toysoldierman,
Sorry, but I agree with Jeff for the same reason, I suspect that a specialised Monsters/Horror forum would be under-utilised.
The Sci-Fi forum was not the only option suggested - I believe that most respondents in the other thread suggested that both Sci-Fi and Figures.forums might be suitable alternatives.
I would lean towards figures rather than Sci-Fi, considering that many of the "classic" monsters are essentially figures. Construction, painting and detailing techniques are essentially identical. The scope of the Figures forum is rather broad - it covers historical and fantasy figures and wildlife - including dinosaurs. I'm sure that monsters and horror subjects would fit right in.