How about nominees for the best performance by a child in a horror movie.

I'll start it off with little Danny Lloyd as Danny Torrence in "The Shining"

I see your creepy child and raise you:

Linda Blair in The Exorcist,

and

Daveigh Chase(Samara) and David Dorfman(Aidan) in The Ring

Miko Hughes as Gage in Pet Sematery

or

Alex Vincent as Andy in Child's Play

or

the creepy kid in the Omen, Damien (cant remember the actor's name offhand)

The Creepy Blonde Children from Village of the Damned

The cute little vampire girl in the Interview with a Vampire

He was great

"I want play with YOU Daddy"

That was Kirsten Dunst.

And who can forget the "even cute when dirty" Newt from Aliens. "They mostly come at night... mostly..."

Played by Carrie Henn.

I always thought that Drew Berrymore did a great job in Firestarter.

Lance Kerwin in Salem's Lot--the original with David Soul.

Absolutely, I still get a nice little chill running down my spine in that bit where Ripley tries to comfort her by saying that there are soldiers there to protect her now, and she says very calmly, "It won't make any difference."

How about the little boy in Halloween who asks Jamie Lee Curtis at the end, "Was it the boogy-man?"  Also, the little girl in Night of the Living Dead who stabs her own mother to death.  Pretty horrific scene.  That little girl now has her own web-site dedicated to Night of the Living Dead.

what's the site?--that scene was possibly one of the most horrifying scenes ever filmed up to that point in '68.  A child murdering her own mother was not too common in movies back then.

Samara from the Ring

The little boy in Wes Cravens: New Nightmare does a pretty good job even if the movie sucked.

Don't forget about the little girl in "Poltergeist".  Great performance and such a tragedy.  Her name was Heather but her last name escapes me.

Heather O'Rourke, and yes great performance (her "They're heeeeere" will always be a classic I just saw it voted one of the top 20 all time greatest movie quotes) and tragically she was another young actor taken too early

Can't believe no one's mentioned Haley Joel Annoyi--er, Osment in Sixth Sense.

.

And Jeremy Licht, the kid who played Anthony in that Twilight Zone episode where he can wish you away to the cornfield if you don't kiss his ass. (I liked the original better than the movie version, though.)