Ankle Drag

Alice is walking alone through the forest/ghost mansion/whatever when suddenly she hears a noise. Ominous music starts playing as she looks around, obviously scared. Then suddenly, something jerks her down to the ground and starts to pull her away at her ankle, likely to a shadowy place. She screams for help, kicks at whatever has grabbed her and tries to get hold of something, dragging her fingers over the ground as she goes. Expect a death scream as she disappears in the shadow.

A variation occurs at a swamp or lake, where something suddenly latches around Alice's ankle and instantly drags her down under. This is often followed up by an underwater camera shot showing Alice struggling and flailing as she inevitably drowns.

The key point here is the fact that Alice aways gets dragged by her ankle, never by any other body part.

May lead into a horizontal Take My Hand-like scenario as Bob tries to rescue Alice.

Examples of Ankle Drag include:

Anime and Manga

In Pokémon Special, just as Courtney tries to tell Ruby about the truth about his father, a tentacle grabs her ankle and drags her into the Cave of Origins just as said cave collapses on her.
Done to Sango in the third Inuyasha movie, but was saved by Kagome.
R.O.D the TV: After collapsing a passageway, Maggie gets pulled into the chasm by a paper whip via her ankle.

Film

Dr. Facilier and Naveen in The Princess and the Frog.
This is the last frame of Quarantine.
Taken: The girl is under the bed, panicking, on the phone, when suddenly she is dragged out by her ankles. Not to her doom, but... yikes.
The bag boy in The Mist.
Happens in the Spider-Man movies when Doctor Octopus' tentacles first go nuts.
Happens to Ripley at the end of Aliens, but she manages to get free at the last moment.
According to its trailer, this will happen at least twice in The Darkest Hour.
Just right before attacking Bruton, the Carnotaurs from Dinosaur actually drag a small Pachycephalosaurus to its doom.
Rattlesnake Jake actually does this to the Mayor at the end of Rango after everyone finds out that he was the villain.
In The Descent, a monster drags off one of the victims by her feet.
In Sorority Row one of the main characters is sent to turn off the overheating jacuzzi, which has created a giant mass of bubbles, while her sorority sisters go into the house. Soon thereafter, appears at a glass door, begging to be let inside after apparently being chased by the Killer. Unknown to her, a thick wire has become tangled around her ankle, and before the other characters can get to her, she is violently dragged off to her doom.
Cthulhu. Happens to the protagonist; he's knocked out by a villain and wakes up to find himself being dragged into a dark doorway by something, but manages to break free.
While the dragger is not seen either time, the demon in the Paranormal Activity films drags Katie out of bed by an ankle in the first movie and Kristi out of Hunter's nursery, down two flights of stairs, and into the basement in the second.
This is done to Woody by Lotso in Toy Story 3.
- Also done to Ellen in a deleted scene from The Incredibles; thankfully for her it was All Just a Dream.

Literature

Ron Weasley in Harry Potter and the Prisoner of Azkaban when he gets kidnapped by the Grim/Sirius Black.
In Xanth, the hairy-armed (and he's nothing but hairy arms) Monster Under the Bed lives for this.
This happens to Gandalf after the battle with the Balrog in The Lord of the Rings, though he was actually grabbed at the knees.
- Also in The Lord of the Rings Frodo is grabbed by the Watcher in the Water.

Live-Action TV

Being Human: Among other resistant ghosts in the series, this happens to Annie at the end of season two. Strangely, the viewer can see the character's ankles and there's visibly nothing physically pulling the victim through the door.
Supernatural: This happens quite often to the victims of the week, usually into sewerage systems or under cars. Or both.

Video Games

In Dead Space, there is a monster that grabs its victims by the ankle and pulls them down corridors. The player has to kill it before it drags Isaac to its mouth and eats him.
This is how you meet Sigrun in Dragon Age Origins: Awakening, as she's being dragged away by darkspawn.
If Heather dies in Silent Hill 3, her corpse is sometimes seen to be dragged off screen by Valtiel via the ankles, presumably to resurrect her.
- If you try to cross a bridge over water inhabited by...something without first killing it, Heather will also be dragged off the bridge and die this way.
Early on in Resident Evil Code: Veronica you see a zombified soldier dragged under a hut by something.
Quite a few people suffer this in F.E.A.R..
Prototype: When Alex Mercer hijacks a tank, a possible animation sees him rip the hatch open, leap inside, and a member of the hapless tank crew crawl from the hatch and almost make it over the edge of the tank before Alex reaches out and drags him back inside by the ankle. Then screaming happens. And a lot of blood.
Happens to the second-to-last SWAT member in Nightmare House 2 when he's standing near a semi-open shutter.
Done twice to Lara in the E3 demo of the Tomb Raider reboot. If you fail, it's an instant death.
In Final Fantasy VIII, an anacondaur monster does this with a wounded Dollet soldier in the Dollet Comm Tower mission.

Western Animation

Code Lyoko: Done to Yumi right after the infamous vine scene.
WITCH: Happens to Will three times across the series, once by quicksand and twice by the Tracker.