Brian Aubrey Marshall (born 24 April 1973) is an American musician best known as the bassist and co-founder of the rock bands Creed and Alter Bridge.

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.

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.

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.

Singer Matt Knabe, who had previously performed in a band called Project Simon, later joined and the newly formed quartet began recording songs.

Marshall attended Choctawhatchee Senior High School (1988–1991), Tallahassee Community College (1991–1993), and Florida State University (1993–1995), where he graduated with a bachelor's degree in interior design.