Far too many to mention but one in particular that I believe to have reached the level of 'greatness' was Lee Ingleby in the role of "Stan Shunpike"... the ticket taker on the "Knight Bus" introduced in the Prisoner of Azkaban.
And then there a scenes, or even moments, individual lines delivered with such sublime acting prowess that I was stunned... I'm thinking of Robert Hardy as Conelius Fudge, (Minister of Magic), when Harry meets him in the Leaky Cauldron.... but these are innumerable over the course of all 8 of the movies.
Alan Rickman was perfect... but then, so were many others. As I mentioned Brendon Gleeson as Madeye Moody floored me the most.
They also managed to pull off one of the greatest feats in movie making history when they had to replace Richard Harris with Michael Gambon as Dumbledore. I liked Harris better but that's no knock on Gambon... who stepped up to the plate in relief and delivered.
