Billy Boyd (born 28 August 1968) is a Scottish actor and musician most widely known for playing the character Peregrin "Pippin" Took in the film adaptations of The Lord of the Rings and Barrett Bonden in Master and Commander: The Far Side of the World.
Dominic Monaghan (born 8 December 1976) is an English actor. He has received international attention from the success of playing Merry in Peter Jackson's adaptation of J. R. R. Tolkien's The Lord of the Rings and his role as Charlie Pace on the television show Lost.
They met on the set of Lord of the Rings in 1999, where they played two little hobbits; and became great friends in the process. If you want proof of this; watch the Lord of the Rings commentaries/extras.
Taken from Wikipedia