Her best known roles are Marita Covarrubias in the movie\/series The X-Files and Andrea in The Walking Dead . She co-starred Jim Carrey in The Majestic movie , played Cybil Bennett in horror movie Silent Hill and Amanda Dunfrey in The Mist . She is perhaps best known for her roles as Marita Covarrubias on The X-Files , Adele Stanton on The Majestic , Cybil Bennett on Silent Hill , Amanda Dumfries on The Mist , Olivia Murray on The Shield , and Andrea on The Walking Dead .