You should read this great essay by China Miéville about the connections of—and differences between—two opposing categories of sci-fi/fantasy: The Weird, which Miéville has championed in the past, and Hauntology, which reimagines ghosts into something that, in the words of Lovecraft, are "lean, dwarfish, and hairy – a sluggish, hellish night-abomination midway betwixt beast and man – and usually touched before it is seen." It's a sharp, funny, highly literate exploration:

Dickens thinks nothing of jostling together, in ‘A Christmas Carol’, the ghost of a person, Jacob Marley, with those of various Christmases. To post-hauntological eyes this is a category-error, but Dickens is merely subordinating the specifics of the ghost to his extreme and mawkish extrapolation of the preceding epoch’s tendency to morally ‘mean’ with spectrality. In neither ‘The Haunted House’ (1859) nor ‘The Haunted Man’ (1848) are the haunts revenants of the dead, but ‘of my own innocence’, or a doppelganger who performs a selective mnemectomy so the story can thumpingly moralise that it is important to remember wrong done to us ‘that we may forgive it’. Dickens’s ghosts are apotheoses of the instructional ghosts of the preceding century – out of time, rearguard in their sentimentality, themselves haunted by the future. They are not so much convincing, morally, as performatively flourished. These are not modern ghosts, but the last, already-dead walking dead of a dead epoch, bobbed about on sticks.

There's much more, including thoughts on H.P. Lovecraft, Jules Verne, Victor Hugo, and octopuses ("it has no claws, but deploys vacuum as a weapon; it eats and shits with the same orifice ((supposedly)); it swims and walks and crawls...[and Hugo insists that they] demand a rethinking of philosophy.") Go read the whole thing.