Walter, I think I inadvertently ignored your question about Paradise Lost. Certainly it contains elements of horror--Mary Shelley's creature in Frankenstein uses Satan as a comparable pathetic creature, but then, Satan is both antagonist and hero--an anti-hero--and created what we refer to as the Byronic anti-hero, the brooding, conflicted villain/main character who ethically we must oppose, even if we can have sympathy for the devil. We understand his motivation for opposing God, but that doesn't make it right or good, just as Shelley's creature must die. They are Uncanny, but also Abject, rejected in human and spiritual society. You could take a Darwinian stance that this is part of herd mentality, the survival of the fittest, in singling out certain unfit candidates for ostracization. In novels like Heart of Darkness, the horror comes from the European heart which has imperially imposed a system that natives must reject, because it is tyrannical, but which individual members of its society discover, in dramatically ironic fashion, that they are the sources of the horror they fear. So, yes, I suppose you could argue that the son of perdition is the chief character in a work of horror, certainly on an epic scale.