via press release:
Academy Award®-winning actress Mary Steenburgen has been cast in FX’s hit series. She will play “Katherine Hale,” a beautiful, southern belle who was the wife of Wynn Duffy’s (Jere Burns) mentor in crime. She will first appear in the 10th episode of this current 5th season and will recur for the rest of the season. Steenburgen is repped by Management 360 and UTA.