McGraw, perhaps best known as Don Draper's mistress in "Mad Men" Season 2, will debut as Deborah in an April episode, and knowing what we know of husband Hollis -- the man responsible for rigging Fitz's (Tony Goldwyn) election -- we're guessing she's got her fair share of dirty laundry stashed away.
In other casting news ...
"Terriers" actor returns to "Sons of Anarchy." Donal Logue -- who played former U.S. marshal Lee Toric in Season 5 -- will reprise his role in Season 6 of the FX drama. [The Hollywood Reporter]
"Nashville" recruits a "Person of Interest." Susan Misner will play a vet who will romance Deacon (Charles Esten) for a few episodes of the ABC musical drama this season. [TVLine]
"Entourage" alum joins "Dexter." Rhys Coiro (who played Billy Walsh on the HBO show) will play a bail jumper being tracked by Deb (Jennifer Carpenter) in the Showtime thriller's eighth season. [THR]