I'm not shooting for an even ten here, just trying to think of essentials.

Pre-1970:

-Black Sunday
-the Abominable Dr. Phibes
-(Karloff)Frankenstein, Bride of Frankenstein, the Mummy
-(Lugosi) Dracula
-(Lee) Horror of Dracula
-Psycho
-Cat People
-Night of the Living Dead

Post-1970:

-Texas Chainsaw Massacre (1974)
-The Shining
-Evil Dead
-Phantasm
-Exorcist
-Halloween
-Ringu
-Suspiria

just pickin'. That was Willy's response to bart when he called it the Shining.

oh haha. i vaguely remember that episode.

so what i spelled it wrong i type fast.

• Texas Chainsaw Massacre 1 and 2
• Halloween 1 and 2
• George Romeros Dead Trilogy
• Evil Dead Trilogy
• Friday The 13th series
• Herschell Gordon Lewis Blood Trilogy(Blood Feast / 2000 Maniacs / Color Me Blood Red)
• Lucio Fulci Films, New York Ripper and Don't Torture A Duckling
• Pieces
• Hellraiser 1 and 2
• The Hills Have Eyes
• Last House On The Left

More than ten but some good movies.

exorcist
rosemarys baby
NOES
friday the 13th
halloween
poltergeist
evil dead series
hellraiser
bram stokers dracula

those r my picks but there r so many great horror movies out there it was hard to come up w/ just 10

top 10 movies a horror newbie should own eh? well i would have to say.
1.)The Thing (carpenter one not the dead old one)
2.)House of a 1000 corpses (a modern day classic)
3.)The Evil Dead Trilogy
4.)Friday the 13th (all of em - but if they make a collection it may be worth waiting as the exsisting DVDs are pretty bare bones apart from the Region 2 UK version of Part 1)
5.)Ichi the Killer (it's so wacked out)
6.)Aliens Quadrilogy
7.)The Nightmare on Elm collection (i know you have it but it is a must have so good choice)
8.)Re-animator (all three of those bad boys)
9.)Hellraiser (The first three at least)
10.)Braindead (buckets and buckets of gore and laughs - it's also known as "Dead Alive")

My top ten are:

1. Evil Dead Trap
2. Evil Dead
3. Friday the 13th (1 & 2)
4. Interview With a Vampire
5. Day of the Dead
6. Howling
7. Silver Bullet
8. Ichi The Killer (Uncut Version)
9. Texas Chainsaw Massacre
10. Nightmare on Elm Street

Sleepaway camp
Sleepaway camp 2 unhappy campers
sleepaway camp 3 teenage wasteland
Don't go in the wood's
the prowler
Madman
Maniac
halloween
halloween 2
friday the 13th 1-5
A blade in the dark

No Children of the Corn???? I know it doesn't scare me or anything, but then again, neither does Evil Dead or any other "horror" movie. I'm sorry, but Children of the Corn had more impact in cinema than a ton of the movies listed in this thread.