Matthew Lewis, from left as Neville Longbottom, Emma Watson as Hermione Granger, Rupert Grint as Ron Weasley and Daniel Radcliffe as Harry Potter. Warner Bros. Pictures Lord Voldemort and Harry ...

Neville Longbottom's crucial backstory adds depth ... series is crucial as they get people talking. Plus, it wasn't part of the movies, so it's something that would take many people by surprise.