Executive producers Robert and Michelle King reveal that Reaser, 35, will play Tammy, a sports writer who will serve as a new love interest for Will (Josh Charles). Taylor, 43, will play Donna Seabrook, a possible romantic foil for Kalinda (Archie Panjabi).
Reaser will first appear on the CBS legal drama on Oct. 19, while Taylor's first appearance is slated for November.
In addition to her role as Esme Cullen in Twilight, Reaser is best known for her work on Grey's Anatomy and the short-lived series The Ex-List. Taylor has starred on series such as Six Feet Under, and most recently appeared in Public Enemies.
The Good Wife returns for Season 2 on Tuesday, Sept. 28 at 10/9c.