Everyone knows Iron Man and Paranoid, but have you ever heard the First Song from the First Album by Black Sabbath? The name of the song is also Black Sabbath!
Their first album was also called Black Sabbath and it was recorded in one day in late 1969. The album cover is as creepy as the music! Black Sabbath created Doom Metal with this album and contributed greatly to Heavy Metal.
The entire album is cool and they style does vary a bit. But this creepy first track is Perfect to get you in the mood for Halloween! The lyrics are shown in the YouTube video description if you want to sing along. :D
Bonus track! This is the 4th song from the Black Sabbath album, and it is called N.I.B. The song is told from the point of view of Lucifer as he courts a woman. The song is less creepy than you might imagine, from the subject matter. It's a pretty awesome 6 minute metal tune with some double tracked lead guitar parts. This is a lyrics video so you can sing along. Rock on! \m/