Actually most of them do. Bonnie Wright only does preprints & I believe it's the same for Rupert Grint. Daniel can be hit or miss, same with Emma. Most of the "smaller" cast actors do though. :) Matthew Lewis, Michael Gambon, Maggie Smith, David Tennant, David Bradley, Emma Thompson, Kenneth Branagh, etc all sign, but it might very well take a while to get their autos back depending on how busy they are.

Which cast members of the Harry Potter movies sign authentic TTM?

Thanks