Mellotron

A mellotron, played by the right musician, sounds like the soundtrack to the end of the world when the demons run amok in the streets and children cry for their lost parents.

Some albums recorded with a mellotron (some evil sounding, some not so much) that I have listened to:
The Beatles - Revolver, Magical Mystery Tour & The White Album
Black Sabbath - Volume 4
David Bowie - Space Oddity, Hunky Dory & Diamond Dogs
Genesis - Nursery Cryme, Foxtrot & Selling England By The Pound
Joy Division - Closer
King Crimson - Just about every album but best sounding on the first album, In The Court Of The Crismon King and on Larks' Tounges In Aspic
Led Zeppelin - Houses Of The Holy & Physical Graffiti
The Mars Volta - De-Loused In The Comatorium & Frances The Mute
Monster Magnet - Dopes To Infinity
Moody Blues - Days Of Future Past
Oasis - "What's The Story" Morning Glory
Opeth - Damnation & Ghost Reveries
Pink Floyd - A Sucerful Of Secrets, Ummagumma and Atom Heart Mother
Porcupine Tree - In Absentia & Deadwing
Radiohead - OK Computer
Red Hot Chili Peppers - Californication & Blood Sugar Sex Magic
Rolling Stones - Beggar's Banquet
Roxy Music - For Your Pleasure & Stranded
Smashing Pumpkins - Most of their albums
Soundgarden - Superunknown
Strange Advance - World's Away
Talk Talk - The Colour Of Spring
Tangerine Dream - Most albums from the 70's but I especialy like Stratosfear
The Tea Party - All their albums
Traffic - Mr. Fantasy

Any parts of these albums that make you sad or fearful were most likely made by the mellotron.