Didn't see it mentioned elsewhere, so I think it's time to bring under your attention the strike of genius that the H. P. Lovecraft Historical Society, a group of devotees of Lovecraft, that evidently possessed by a Great Old One they came up with the idea of mixing Christmas songs with Lovecraft myths.
The result is an absolutely hilarious mashup of Christmas songs (which are essentially played as the original, the point here is not a new musical arrangement, but the lyrics) with Lovecraft themed lyrics, and two Christmas albums were spawned:
A Very Scary Solstice (
https://en.wikipedia.org/wiki/A_Very_Scary_Solstice )
An Even Scarier Solstice (
https://en.wikipedia.org/wiki/An_Even_Scarier_Solstice )
Even reading the titles is funny, and most of them give away the original song they've based on.
Listening to two albums worth of material may be tiresome, so if you don't know where to start, I offer you my very very scary worst of, which I always play around this time, 15 minutes or less of madness, christmas and insanity:
The Carol of the Old Ones -
https://www.youtube.com/watch?v=aB39OqlJsm4Chtulu Lives! -
https://www.youtube.com/watch?v=THEFl1h2-XAAwake Ye Scary Great Old Ones -
https://www.youtube.com/watch?v=ccefqYQWtdAThe Shoggoth Song -
https://www.youtube.com/watch?v=BeqW3uG-rbQAway in a Madhouse -
https://www.youtube.com/watch?v=WnG8nOK7nqMOh Come All Ye Old Ones -
https://www.youtube.com/watch?v=g2DscvVye94Demon Sultan Azathoth -
https://www.youtube.com/watch?v=xHAeJSwUbawDeath May Die -
https://www.youtube.com/watch?v=H9o8OWVWOE0Silent Night, Blasphemous Night -
https://www.youtube.com/watch?v=d0zHQqp8LPsSilent Night Blasphemous Night is actually my favorite. The contrast between the mood of the song, played straight with a delicate piano melody and sweet singing, and the lyrics about Chtulu coming to enslave all mankind is absolutely hilarous.
Have yourself a scary Christmas!!!