Delany, best known for her performance as Diane Russell on "NYPD Blue," will play an ex-flame who comes back into the life Peter Gallagher's character, Sandy Cohen. Delaney is set to appear in five episodes of the prime time soap that returns to Fox Thursday night for its second season.
In other casting news, Teri Polo of "Meet the Parents" is joining "The West Wing" in a recurring role. She will play the wife of Matthew Santos played by Jimmy Smits -- a three-term Democratic congressman from Texas who aspires to the presidency.
Variety said Polo would do four episodes of "The West Wing" this season, and has an option for 12 more episodes if the White House drama gets a seventh year on NBC.