Creed

After being recruited into the band as a full-fledged member by Scott Stapp and Mark Tremonti, Marshall came up with the name Creed after a band he was in earlier called Mattox Creed which had since disbanded. He was in Creed until late 2000, when personal issues with vocalist Stapp led him to depart the band, though some sources state that Marshall was fired. Marshall, however, remains silent about this issue and does not state the reasoning behind his departure.

Brett Hestla from the band Virgos Merlot, replaced Marshall for the tour. For Creed's third album, Weathered, guitarist Mark Tremonti played bass and Brett Hestla played bass during live performances.

After months of speculation, Creed announced in April 2009 that they had reformed, and also announced that Marshall was back in the band. He appeared on Full Circle, the Creed album released in October 2009, making it the first album since Creed's sophomore release, 1999's Human Clay, to feature him on bass. The band toured in support of Full Circle throughout the United States, Canada, Europe, Australia, and South America during the summers of 2009 and 2010.

Alter Bridge

When Alter Bridge started getting off the ground in late 2003, Marshall was asked by Tremonti and former Creed drummer Scott Phillips to join the band since they enjoyed his playing and company.

Other projects

After leaving Creed in 2000, Marshall stated that he had taken some time off before he later got back into music. In 2001, he began writing and recording music with a band he formed called Grand Luxx, featuring his former Mattox Creed band mates, guitarist Dan Bartley and drummer Hardy Mattox. Singer Matt Knabe, who had previously performed in a band called Project Simon, later joined and the newly formed quartet began recording songs. Marshall stated, "I'd say our music is rock, but it's very eclectic, and I think it can reach a wide audience. We have a little bit of alternative and some hard-rocking guitar riffs too. And Matt brings in some pop flair because his influences were bands in that genre." He also stated that with Grand Luxx, he had "kind of moved to a different role" and did more work on the production side. By July 2001, the band, having played a few shows, had six songs written with initial plans to record an album that fall. Some of Grand Luxx's original songs include "Stagnant" and "Insomniac's Dream."^[2][3] Also during this time, Marshall was in a band called Head Heavy with vocalist Maceo Morris, Dan Bartley and James Thatcher. The band completed a full length recording at Marshall's home studio but it was never formally released to the public.

In 2012, Marshall joined Mark Tremonti's solo band Tremonti but due to personal reasons he left the project and was replaced by Wolfgang Van Halen in September 2012.