Michael `` Mike '' Edward Mills ( born December 17 , 1958 ) is an American multi-instrumentalist and composer who was a founding member of the alternative rock group R.E.M. Though known primarily as a bass guitarist , backing vocalist , and pianist , his musical repertoire includes also keyboards , guitar , and percussion instruments .
Michael Edward `` Mike '' Mills ( born December 17 , 1958 ) is an American musician , singer and songwriter .