Ok, here goes....
I've just moved recently and all my DVD's mixed up and stacked on shelves up against the wall, one right next to the other [the shelves]. This makes the DVD's hard to get to and a real pain-in-the-ass to read, so I'm SURE I've missed some obvious ones here...
But in any case here is sort of an 'undifinitive' list of horror movies that feature young girls, SOMEWHAT catagorized by prominance and [as well as I can remember] whether they contain OT scenes [in most of the 'bath' scenes, they are shot for modesty

]...
Children are main or pivitol Characters:
*Innocence - Yes, I think this is a VERY chilling piece of understated horror!!! LOTSA OT!

*Paperhouse - Bath scene
*Veneno para las hadas - Bath scene
*El Libro de piedra
*El Laberinto del fauno - Bath scene
*Do Not Disturb - More of a thriller -
http://www.imdb.com/title/tt0185284/
*Bloody Birthday
*Devil Times Five
*Who Slew Auntie Roo? - Chloe Franks
*Ginger Snaps II
*The Brood - Bath Scene - Cindy Hinds
*Pinocchio's Revenge
*In the Cold Light of Day - Mom carrying dead child - Perdita Weeks
*Alice, Sweet Alice
*Aliens - Carrie Henn
*The Tooth Fairy
*Red Riding Hood
*Poltergeist I, II, & III - ?Bath scene in the 1st?
*Doctor Sleep [Close Your Eyes]
*The Darkling
*Plenilunio [Luna Llena - Full Moon] - Dead child - Victim stumbling away from crime scene
*Escarnio
*Honogurai mizu no soko kara [Dark Water]
*Dark Water - Bath scene, I think
*War of the Worlds - Dakota Fanning
*Hide and Seek - Dakota Fanning
*The Reaping - There IS a bath scene here!

- Anna Sophia Robb
Others [Children present, but in lesser roles]:
*Brotherhood of Satan - Cute, short dresses... lol
*Bless the Child - 2000
*The Bad Seed
*Mommy
*Mommy 2: Mommy's Day
*Element of Crime
*The Pledge
*The Sight
*The Rats
*The Wild Beasts - Girl putting on a blouse
*The Nameless
*Fragiles
*Troll 2
*The Turning of the Screw [These 5 movies are related by story; I'm sure MORE versions of this were filmed, also]
*The Innocents
*The Nightcomers
*Presence of Mind
*In a Dark Place
*Dolly Dearest - Candace Hutson
*The Maddening - Candace Hutson
*The Amnityville Horror - Chloe Moretz
*Wicked Little Things - Chloe Moretz
*Un jeu d'enfants
*Deadline - Cindy Hines
*¿Quién puede matar a un niño? [Who Could Kill a Child?]
*Children of the Corn - The first one is really the only one worth a shiite...

*Chi l'ha vista morire? [Who Saw Her Die?]
2 Actresses that seem to shine in horror:
**Jodelle Ferland Movies:
http://www.imdb.com/name/nm0272706/ [Her roles are usually not very big in most of the horror films she's in...

]
**Nicoletta Elmi Movies:
http://www.imdb.com/name/nm0255435/ [Much used actress in the Italian 'giallo' slasher flicks. Usually not much screentime, but she's such a cute redhead!!]
Again; this list is by no means 'difinitive' and ESPECIALLY in no real order!! I typed them up as I remembered them [along with those I wrote down from the DVD's I looked over...

]
Please add whatever I missed!
kev.