The Raven represents death, and how that feeling of sadness will always be there. "And my soul from out that shadow lies floating on the floor Shall be lifted-nevermore!" (Poe 317)
supernatural or otherworldly elements
He is sitting alone in his house. "Once upon a midnight dreary, while I pondered, weak and weary, Over many a quaint and curious volume of forgotten lore-" (Poe 312)
"Take thy beak from out my heart, and take form from off my door! Quoth the Raven, "Nevermore." " (Poe 317) The Raven won't leave and the man wants him to, so that's why he says take thy beak from out my heart. The bird being there is almost taunting him about the death of his wife, so he wants him to leave.
characters in psychological and/or physical torment
The Raven being able to talk is supernatural. "Quoth the Raven, "Nevermore!" " (Poe 314) In reality a raven could never talk to someone if they talk to them.
"And the Raven, never flitting, still sitting, still is sitting on the pallid bust of Pallas just above my chamber door" (Poe 317) This is saying that death will always be with you, and the pain and emotions you feel will always be there in some way.
"This I whispered, and an echo murmured back the word, "Lenore!" " (Poe 314) He is grieving over his dead wife, and when he said her name he heard it being said back to him made him sad. This could be torment toward him after losing his wife.