Born in Okinawa, Shepherd grew up in Washington and developed an interest in music after watching Johnny Cash on TV. He played in various punk-rock bands and eventually joined Soundgarden as a bassist in 1990. Shepherd contributed to the band's musical evolution and played a significant role in songwriting. In 1993, he formed a side project, Hater, with Matt Cameron and John McBain. Soundgarden broke up in 1997, leading Shepherd to struggle with addiction and personal issues. He played in various bands before Soundgarden reunited in 2010, continuing until Chris Cornell's death in 2017.