Roberto Agustin Trujillo (; born October 23, 1964), better known as Robert Trujillo, is an American musician known for his role as the current bassist of heavy metal band Metallica. He also was a member of crossover thrash metal band Suicidal Tendencies, funk metal supergroup Infectious Grooves, heavy metal band Black Label Society, and he has worked with Jerry Cantrell from the grunge band Alice in Chains, and Black Sabbath vocalist Ozzy Osbourne. He is currently touring intermittently with experimental metal group Mass Mental.