Bassist best known as the original bassist for the thrash metal band Metallica. He is also known for his time spent in the band Phantasm.
He joined his first band, Leather Charm, in June 1981.
He left Metallica in the early 80's due to personal tensions between he and other members of the band.
He has sons named Justin and Tyler.
He was replaced as the bassist for Metallica by Cliff Burton.