Death (Discworld)
Death has appeared in every Discworld novel, with the exception of "The Wee Free Men" and "Snuff", and had a possible cameo at the end of "Johnny and the Dead" (the character was not identified, but spoke in unquoted small caps). The Discworld books with Death as a leading character, starting with "Mort" in 1987, are:
Magic in Harry Potter
Death is studied at the Department of Mysteries in a chamber containing an enigmatic veil, which Rowling has described as "the divide between life and death". With regard to what is on the other side, she elaborated: "Do I believe you go on? Yes, I do believe you go on. I do believe in an afterlife, although I'm absolutely doubt-ridden and always have been but there you are." Sirius falls through this veil in "Order of the Phoenix" after he is hit with a curse from Bellatrix.