Roberto Agustín Miguel Santiago Samuel Trujillo Veracruz is an American musician who has been the bassist for heavy metal band Metallica since 2003. He first rose to prominence as the bassist of crossover thrash band Suicidal Tendencies from 1989 to 1995, while also collaborating with Suicidal Tendencies frontman Mike Muir for funk metal supergroup Infectious Grooves. After leaving Suicidal Tendencies, he performed with Ozzy Osbourne, Jerry Cantrell, and heavy metal band Black Label Society. Trujillo joined Metallica in 2003 and is the band's longest-serving bassist. He was inducted to the Rock and Roll Hall of Fame as a member of Metallica in 2009.

Michael Allen Muir is an American singer who is the lead vocalist and the sole continuous member of Los Angeles-based bands Suicidal Tendencies, Los Cycos, and Infectious Grooves. He has also released several solo albums under his nickname Cyco Miko. Muir's trademark is wearing bandanas, jerseys with the number 13, and hats with block-style letters that read "suicidal".