ozzy osbourne, mercyful fate/ king diamond, helloween ("halloween"!), dio, venom...

UH-OH!!! Now You went and Got me Started!!!!

I LOVE DJ-ing Halloween parties!! They're my Fav!!!
If you can find them here are a few good CD's :

"New Wave Halloween" - Various Artists [features: Ministry, Ramones, Misfits and More!]

"Halloween Hootenanny" - Various Artists [features: Rob Zombie, Reverend Horton Heat, Swinging Neckbreakers and More!]

"Halloween Hits" - Various Artists [Has a lot of the older novelty stuff like "Monster Mash", "Purple People Eater"...etc...]

"Dr. Demento Presents- Spooky Tunes & Scary Melodies" - Various Artists
A lot of Horror Movie soundtracks got good stuff on them such as:

"Jason -Vs. Freddy", "From Dusk Til' Dawn" etc...

Other suggestions :
ANYTHING by Alice Cooper is great !!!! ["Welcome To My Nightmare", "Pick Up The Bones", "Go To Hell", "Dead Babies", "Teenage Frankenstein", Feed My Frankenstein" etc...]

Throw some Rob Zombie/White Zombie, Marilyn Manson in there...

"Werewolves of London", "Roland The Headless Thompson Gunner" - Warren Zevon

"Munsters Theme" - The White Pigs

"Witch Hunt" - Rush

"Scary Monsters" - David Bowie

"D.O.A." - Bloodrock

"Old Man Down The Road", "Eye of the Zombie", Wicked Old Witch" - John Fogerty

"Don't Fear The Reaper", "I Love The Night", Nosferatu" - Blue Oyster Cult

"Sisters of the Moon" - Fleetwood Mac

"Zombie Zoo" - Tom Petty & The Heartbreakers

"Spirit In The Night" - Bruce Springsteen

"Season of The Witch" - Donovan

"Thriller" - Michael Jackson [Always a great on for Halloween parties!] as is

"The Time Warp" - Riff Raff [Rocky Horror Picture Show]

"The Boogie Man", "Night Prowler" - AC~DC

"Boris the Spider" - The Who

"Vampire" - Peter Tosh"

"Pet Sematary" - The Ramones

"Goo Goo Muck" & "Rockin' Bones" - The Cramps

"House On The Hill" - Audience

"Legend of Wooley Swamp" & "Devil Went Down To Georgia" - Charlie Daniels Band

Throw in some comic relief with some "Monster Mash" and "Purple People Eater".

All else fails, look up some vintage Alice Cooper.