|First appearance||16th June 2003|
|Last appearance||20th March 2005|
|Number of appearances||121|
|Played by||Tina Gambe|
Sonia Marshall worked at Mike Baldwin's factory, Underworld, from 2003 to 2005. She had a brief romance with resident Martin Platt, their relationship ended and she decided to become a Red Coat at a holiday camp and left the Street for good.