Mentioned in some of the other threads, but a few may bear repeating:
Dry Bones
(Ghost) Riders In The Sky
Monster Mash
Witchy Woman
Ding-dong! The Witch Is Dead
He Had A Long Chain On
Spooky
Flying Purple People Eater
Long Black Veil
The Happy Land (Scots children's song that tells of a ghost
Miss Bailey's Ghost.

I might even throw in Stray Cat Strut or The Cat Came Back. And I think Zombie Jamboree is perfect!

Aren't there any songs about vampires? I know there are a number of werewolf folk songs.* Maybe songs about silkies would be appropriate, too.

Genie

*i.e., folk songs sung by werewolves

*