is Aragorn, but there were several who were (IMO) unnecessarily changed from their book characters--Faramir, Denethor, Merry, Pippin, Galadriel, Gimli, Haldir, etc., etc.
I didn't mind so much when the characters did different things than they did in the book, but when they were changed into completely different personalities, that's when it didn't go down so well.