Dark Romanticism refers to a subgenre within the romantic movement that dominated literature and the arts between the late eighteenth century and first half of the twentieth in both Europe and the United States. Romanticism generally celebrates the individual, nature, and the sublime. Emotion rules over rationality. Dark Romanticism is, as its name suggests, the darker underbelly of this movement: it delves into the irrational, the supernatural, and the grotesque.
Both Edgar Allan Poe's "The Oblong Box" and Nathaniel Hawthorne's "The Birthmark" are straightforward examples of American dark romanticism. Both feature men obsessed with their wives: in Poe's story, Cornelius Wyatt is so grief-stricken over the death of his young wife that he keeps her body in the titular box, opening it every night and seemingly disregarding the odor of her decaying corpse, while in Hawthorne's story the protagonist Aylmer is obsessed with the birthmark on his wife Georgiana's cheek, seeing it as the one thing keeping her from perfection. These obsessions are irrational, but they are decidedly human. Wyatt is grieving and Aylmer is obsessed with an ideal.
In some ways, Aylmer represents Romanticism's darker impulses, much like Shelley's Frankenstein, in his quest for greater control over the natural world. Idealism is often linked with goodness, but here, Hawthorne shows how it can lead to disillusionment and death. Aylmer kills his wife when he removes her mark, suggesting that nature is not to be trifled with.
The dark Romanticism in "The Oblong Box" comes in Wyatt's morbid attachment to the late Mrs. Wyatt's "partially embalmed" body. His extreme grief finally manifests in a veritable death wish: he ties himself to the oblong box during a storm and allows both himself and the coffin to be cast out to sea. He dies for the sake of a body rather than for a living person, and this is undoubtedly grotesque. Like Aylmer, he is opposed to life in all its imperfections and chooses death in the end.