That list feels like something the Guardian would put together by committee. I mean, there's a lot of great horror authors who deserve a mention on that list. Graham Masterton's Manitou - classic? Night Warriors? One of my favourite books of all time.
And Clive Barker gets a passing mention.
I think Mountains of Madness is enormously overrated (good, but not a classic), and World War Z is just really rather rubbish.