This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / Sufjan Stevens
Sufjan Stevens is one creepy cookie. Filled with whispering vocals and exotic, ululating instruments, his music is eerie at the best of times, and when he wants to, it's downright disturbing. Year of the Sheep, for example, consists of soft chorale, gentle strings, electronic effects, and, oh yeah, what sounds like backmasking of a screaming sheep. Not one you want your Winamp shuffling up late at night, or even on a vaguely overcast morning.
"John Wayne Gacy, Jr." is about a (completely real) serial killer who killed 27 teenage boys (according to the song, though the real number of victims may be slightly more or less) and buried them in shallow graves in his cellar. Every line is pure nightmare fuel, but the last verse is particularly chilling.
"The Owl and the Tanager", originally called "Barn Owl, Night Killer", is just as sinister as its working title.
Usually when his Christian faith is brought up in his music it's in the context of a God Is Love Song, but "Seven Swans" is a truly chilling depiction of the Book of Revelation. Most of the song is built around a slightly off-key ukulele riff and cryptic lyrics about signs in the sky and dragons. Then the key change happens and huge, echoing drums come in in the background and the tone of the lyrics changes: