Shannyn Sossamon has been cast in a recurring role as Alex on ABC’s primetime sudser, “Mistresses.”Thesp joins a cast that includes leads Alyssa Milano, Yunjin Kim, Rochelle Aytes and Jes Macallan. Project, based on the U.K. series of the same name, follows four women with scandalous love lives. K.J. Steinberg is on board as scribe and exec producer, and Cherie Nowlan will helm the pilot, scheduled to premiere in 2013 Sossamon has starred in pics including “A Knight’s Tale,” “The Holiday” and “The Rules of Attraction,” and recently wrapped production on “Man Without a Head.” She will be seen in the forthcoming indie film, “The End of Love,” which premiered at Sundance this year and will be distributed by Wrekin Hill. Sossamon is repped by Oren Segal at MPE.