This is a very subjective list as I am not a movie aficionado and there are dozens of great horror movies that I have not seen. But here it is.
Number 1
The Exorcist

I saw this movie when I was 14 years old. Not a good idea. I was an altar boy at the time and therefore still believed in Angels and Demons. This movie so terrified me that I almost went to see a priest to discuss my possible possession by a demon.
This movie takes horror to a whole new level. There is the blatant visceral demonic possession scenes, but at the same time subtle underlying terrifying messages that come at you from all angles.
Number 2
Hellraiser
The Cenobite Demons in this movie are radical. The torture chambers and dark cenobite world is shocking. Pinhead causes cold streams of angst to penetrate your very soul. The Uncle Frank character is a classic. Clive Barker creates a brand new world of horror like nothing that came before.
Number 3
The Shining
Jack Nicholson at his creepy best. What you don’t see in this movie is scarier than what you do see. The Overlook Hotel is the perfect haunted mansion. The horrific history of the hotel is something that the moviegoer will ponder for weeks after seeing this movie.
Number 4
Alien
Great monster, great spaceship, great planet scene, great story and great crew on the ship. Enough said.
Number 5
Black Christmas
Very creepy psycho in the attic murdering sorority girls. A young Andrea Martin is worth revisiting this classic. The strange sounds and noises that the thing in the attic makes is enough to make your hair stand on end.
Number 6
Dawn of the Dead
Zombies run amuck in a shopping mall. Lots of gore which is typical of Zombie movies. After seeing this movie you will never look at a shopping mall the same way again.
Number 7
The Texas Chainsaw Massacre 1974
Very disturbing hillbilly killers who also double as cannibals. These gruesome psychos are on a mission from the Devil himself. Sticking innocent victims on a meat hook is just one of their nefarious techniques. The old grandpa killer is an island of hilarity in this dark tale.
The Grandpa scene, not for the faint of heart.
Number 8
The Silence of the Lambs
The Antagonist in this movie is one of the best of all time. Hannibal the Cannibal Lecter is a genius killer and cannibal. His dispatch of the 2 policeman is done with such cunning and precision that it makes your head spin. Great story combined with amazing characters. A classic.
Number 9
The Thing 1982
One of the most innovative monsters in movie history. This Thing can copy and replicate any biological form. You never know who the enemy is. Your best buddy or pet could be an evil alien life form that wants to eat you whole. Set in the Antarctic on an isolated base this movie leaves you with a very cold chill indeed.
Number 10
The Hills Have Eyes
Grotesque mutants that prey on unsuspecting travellers. This movie has enough blood, guck and gore to nauseate the toughest horror fan. The mutants got this way from exposure to radiation from atomic bomb tests in the desert. They are seeking revenge on the normal folk. And pity the poor normal folk that wander into mutant territory.