Clifford Lee Burton ( February 10 , 1962 - September 27 , 1986 ) was an American bassist and songwriter , best known by being the bassist of thrash metal band Metallica from 1982 until his death in 1986 . Clifford Lee `` Cliff '' Burton ( February 10 , 1962 â `` September 27 , 1986 ) was an American musician , best-known as the bass guitarist for the American thrash metal band Metallica .