Have a team make a life-size frozen Harry Potter scene (or any other movie, i.e. The Jungle Book) and have everyone else guess the scene.
Assorted props, clothes, fabrics
If you have a large enough number and/or audience, it can be quite fun. You choose a scene from one of the books, and the participants have to use what they can find (i.e. in a given pile of clothes, fabrics and other such paraphernalia) to dress up as the characters and act that scene. However, there is no movement – it's like a snapshot, a single frame, so all the participants performing must be still. It's sometimes better if you can fashion a curtain – that way the team can get ready before anyone is watching, so all the audience sees is the ‘still'. Then the audience has to guess what the scene is.
You could make it harder by asking for the book it appears in and/or the chapter. You could make it more competitive by timing how long it takes for the audience to guess – and the winning ‘team' would be those whose scene was guessed the fastest. Or it could be a scene from the movies.
Found on http://www.the-leaky-cauldron.org/features/crafts/potterparties/tableaux/