Jason Curtis Newsted (born March 3, 1963 in Battle Creek, Michigan) is an American bassist known as a former bassist of Metallica. Joining the band in 1986 after Cliff Burton's death, Newsted remained a member until 2001, making him Metallica's longest-serving bassist. After he left Metallica, he continued with his project Echobrain, played with Ozzy Osbourne and joined heavy metal band Voivod. Newsted uses the pseudonym Jasonic, which serves as both his alias in Voivod and the name of his music publishing company. He is also the founder of the Chophouse Records studio and label based in California.

Following the death of Metallica's bassist Cliff Burton in September 1986 on the Europe leg of the Damage Inc. Tour, Metallica began a search for a new bassist. Newsted auditioned for the part along with roughly 39 other musicians and in winning the role, his first live performance with Metallica was at the Country Club in Reseda, California. Newsted was often subjected to pranks and ridicule which increased as time went on. His debut with Metallica was on its extended play The $5.98 E.P.: Garage Days Re-Revisited. This was followed by his first studio album with the band, ...And Justice for All, which was subject to controversy and criticism for its poor production - among other issues, for its murky bass sound.[1] Newsted claims this was further hazing on the part of Lars Ulrich and James Hetfield, although both Ulrich and Hetfield claim they were also disappointed with the production of the album.[1] In addition, they claim that most/all of Newsted's bass lines closely followed the rhythm guitar lines to the point of being indiscernible from each other.[citation needed] Nonetheless, the album reached number 6 on the Billboard 200 and projected the band to higher success.

Newsted performed on ...And Justice for All (1988), the self-titled Metallica (1991), which is the best-selling Metallica album to date and made Metallica a world-known band, Load (1996) and ReLoad (1997). The live concerts Live Shit: Binge & Purge and Cunning Stunts were produced in 1993 and 1997, and S&M in 1999. Newsted also played bass on the song "I Disappear" in 2000.

During his time in Metallica Jason played the bass guitar and also sang backing vocals on numerous Metallica songs. During the tours after 1991 Jason often sang parts of "Creeping Death", "Whiplash" and "Seek and Destroy". He is known for his bass solo which included parts of "My Friend of Misery" and bass parts from his former band, Flotsam & Jetsam.

He has co-written three Metallica songs:

    * "Blackened" (...And Justice for All)
    * "My Friend of Misery" (Metallica)
    * "Where the Wild Things Are" (ReLoad)