In reading "The Raven" in high school, and again for American Literature, I have begun to look at the raven as sort of a personification of Death. Personification is when a non-living object is given human characteristics, or as Merriam-Webster Online defines, "representation of a thing or abstration as a person or by the human form.
I see this as death personified because the raven speaks to the character in the poem, a humanistic quality. He speaks of the "lost Lenore," and to every question the character asks, the raven responds "Nevermore." I think the Raven, Death, has come to take the narrator into the afterlife to be with his love, Lenore. I don't look at the raven as "frightning" or as "the end," I look at the raven as the "bridge," if you will, to the afterlife. I think the Raven wants to take the character to a better place, to a place where he can be with his love for eternitiy. Death is inevitable, and I think Poe is trying to relay the feeling of a near-death experience to the reader. Poe seems to want to make the loom of death easier on the reader, something we should not be afraid of. Death is something that never goes away, or as the Raven says "Nevermore."