Which one of these people has been in the band ''Metallica'' in the past?

The answer is Dave Mustaine because he was the original lead guitarist of Metallica before he was replaced by Kirk Hammett. Mustaine was a founding member of the band and contributed to their early albums and songwriting. However, due to creative differences and personal issues, Mustaine was ultimately dismissed from Metallica. Following his departure, he went on to form the successful thrash metal band Megadeth.