- Bats Left, Throws Left
- Height 6' 5", Weight 185 lb.
- School Virginia Commonwealth University
- High School Manchester High School
Brian Marshall is the twin brother of Sean Marshall. They enrolled at Virginia Commonwealth University together in 2001. While Sean was Colonial Athletic Association Rookie of the Year, Brian had a 2.45 ERA in 12 appearances. In 2002, Brian did the better job, going 6-4 with a 3.08 ERA, 92 K in 79 IP and a CAA-leading 10 saves. He made the CAA All-Conference team. In 2003, Marshall went 5-5 with 12 saves and a 2.81 ERA and missed the conference lead in saves, one behind Blake Cross. Marshall fanned 77 in 51 innings, allowing 36 hits. The Boston Red Sox drafted him in the fifth round of the 2003 amateur draft, one round before his brother was selected.
Brian was assigned to the Lowell Spinners, where he went 1-1 with six saves and a 1.08 ERA, a .72 WHIP and 15 K for 2 walks. In '04, Marshall moved up to the Sarasota Red Sox, where his pitching line read 1-1, 1 Sv, 3.49 with a strikeout per inning.
In 2005, the left-hander was 3-0 with a 2.35 ERA and 12.13 K/9 for Lowell and 1-0 with one save and a 2.08 ERA for the Greenville Bombers, allowing a .116 average. He was released by the team early the next year.