Monaghan was born in Berlin to British parents. He has a tattoo on his right arm of the English word "nine" written with the Tengwar script. It means that his character was one of the nine members of the Fellowship of the Ring in "The Lord of the Rings". Many other cast members also got similar tattoos during the making of the movie. On his left arm is a tattoo that says "Living is easy with eyes closed", a line from The Beatles' song "Strawberry Fields Forever". On "Lost", Charlie's tape/bandage finger-rings with letters spelling out words were Monaghan's idea. He thought that because Charlie is an artist, he would still want to be creative even when trapped on an island. Monaghan also actually plays the guitar on "Lost".