He is well-known for playing Merry Brandybuck in Peter Jackson 's film trilogy of J. R. R. Tolkien 's The Lord of the Rings . He is also well-known for playing Charlie Pace on the television show Lost . He has received international attention from playing Merry in Peter Jackson 's adaptation of J. R. R. Tolkien 's The Lord of the Rings and for his role as Charlie Pace on the television show Lost .