So how many Inferi lie in the lake?
A couple million? Above water, you’d probably see about a hundred at a time. But when Harry gets dragged into the lake, there is a whole underwater environment…and it’s actually covered in bodies. It’s all just ... bodies crawling on top of each other, and that’s how you get into the millions.

That sounds … disturbing. Certainly, more so than the previous “Potter” films.
It’s certainly much bolder and scarier than we imagined that they’d ever go in a "Potter" movie. Director David Yates was really cautious of not making this into a zombie movie, so we were constantly trying to figure out how not to make these dead people coming up look like zombies. A lot of it came down to their movement – they don’t move fast, but they don’t move really slow or groan and moan. We ended up going with a very realistic style. They move like anyone coming up out of water.

How so?
When we go underwater with Harry, this female Inferi kind of comes up and grabs him and is pulling him down, but it’s more like a hug. Like an embrace. Like she’s trying to encourage him to join them. We were always trying to avoid turning the scene into one you’d see in a horror film.

Tell me about how the Inferi look. How did the design come about?
The art department on the film gave us a lot of references, like Dante’s "Inferno," where they have all those bodies. The Inferi themselves are very skinny and emaciated people. Very humanoid, but way skinnier than humans could be. Waterlogged and gray. We used the old lady that comes out of the tub in ‘The Shining’ as a reference. Most of the Inferi are adult, but we did also build two children, too.