Robert Trujillo is an American bassist

Bassist

A bass player, or bassist is a musician who plays a bass instrument such as a double bass, bass guitar, keyboard bass or a low brass instrument such as a tuba or sousaphone. Different musical genres tend to be associated with one or more of these instruments...

 who currently plays bass in Metallica

Metallica

Metallica is an American heavy metal band from Los Angeles, California. Formed in 1981 when James Hetfield responded to an advertisement that drummer Lars Ulrich had posted in a local newspaper. The current line-up features long-time lead guitarist Kirk Hammett and bassist Robert Trujillo ...

. He has also played in Suicidal Tendencies

Suicidal Tendencies

Suicidal Tendencies is a U.S. crossover thrash band founded in 1981 in Venice, Los Angeles, California by Mike Muir, its leader and only permanent member. The band is sometimes credited as one of "the fathers of crossover thrash"...

, Infectious Grooves

Infectious Grooves

Infectious Grooves is a funk metal band led by Suicidal Tendencies frontman Mike Muir. It also features former Excel guitarist Adam Siegel, ex-Suicidal Tendencies bassist Robert Trujillo , and ex-Jane's Addiction drummer Stephen Perkins...

, Black Label Society

Black Label Society

Black Label Society is a heavy metal band formed by Zakk Wylde, with nine studio albums, one live album, two compilation albums, one EP, and three video albums released since formation of the band.-Formation and Sonic Brew :...

, and with Jerry Cantrell

Jerry Cantrell

Jerry Fulton Cantrell Jr. is an American guitarist, singer, and songwriter best known for his work with the grunge/metal band Alice in Chains, as lead guitarist, backing and co-lead vocalist, and co-lyricist. He performs lead vocals on his solo projects, and is part of Alice in Chains' harmonizing...

 and Ozzy Osbourne

Ozzy Osbourne

John Michael "Ozzy" Osbourne is an English vocalist, whose musical career has spanned over 40 years. Osbourne rose to prominence as lead singer of the pioneering English heavy metal band Black Sabbath, whose radically different, intentionally dark, harder sound helped spawn the heavy metal...

.
He was a member of Ozzy Osbourne's band for a number of years starting in the late 90s. Trujillo was the subject of controversy for re-recording Bob Daisley

Bob Daisley

Robert John "Bob" Daisley is an Australian musician, bassist and lyricist who has performed in genres of rock, blues, R&B, hard rock and metal.-Early career:...

's bass tracks for reissued versions of Osbourne's albums Blizzard of Ozz

Blizzard of Ozz

Blizzard of Ozz is the first solo studio album by British singer/songwriter Ozzy Osbourne, recorded in Surrey, UK and released on September 20, 1980 in the UK and on March 27, 1981 in the U.S.. It is the comeback album of Osbourne following his firing from Black Sabbath the previous year...

and Diary of a Madman

Diary of a Madman (album)

Diary of a Madman is the second studio album by Ozzy Osbourne. It was recorded from the 9th of Feb to the 23 of March 1981 inclusively - the end of winter in the UK and recording ending just into spring equinox. It was released on November 7, 1981, and re-issued on August 22, 1995. An altered...

because of Daisley's claim of not receiving proper royalties.