Brad Dourif
From Tolkien Gateway
American Academy Award-nominated actor Brad Dourif (born 1950) played Gríma Wormtongue in Peter Jackson's The Lord of the Rings.
Throughout the filming he stayed totally in character, and only after Peter Jackson called "cut" for the last time did he drop the accent he adopted for the role. When Jackson heard his real accent, he assumed Dourif was just joking around!
