WILLIAMSTOWN — Kate Walsh, Justin Long, Laila Robins, Grace Gummer, Deborah Rush and Brian F. O'Byrne are among a host of actors and actresses who have been added to the roster of performers appearing this summer at Williamstown Theatre Festival.

The season — Mandy Greenfield's second as artistic director — runs June 28 through Aug. 21 on the Main Stage and Nikos Stage at Williams College's '62 Center for Theater and Dance.

Walsh, who is best known as Dr. Addison Montgomery on the TV series "Grey's Anatomy" and its spinoff, "Private Practice," will appear in Wendy Wasserstein's "An American Daughter," Aug. 3-21, on the Main Stage, Joining her in the cast, among others, will be Rush and Gummer.

Rush, who has extensive film and television credits, has performed on stage at New York Shakespeare Festival and the 2005 Broadway revival of Alan Ayckbourn's "Absurd Person Singular."

Gummer, a daughter of actress Meryl Streep and sculptor Don Gummer, counts as her most recent screen appearances roles in "Frances Ha," "The Homesman" and "Margin Call."

Long — who will be in the world premiere of Boo Killebrew's "Romance Novels for Dummies," July 20-31, on Main Stage — is no stranger to Williamstown. He appeared last season in "Legacy" and in "An Intervention." His previous WTF credits include "Living on Love" (2014), "Samuel J. and K." (2010), "One Slight Hitch" (2011) and "The Hot l Baltimore" (2000).


Robins — who will bne co-starring in the world premiere of "The Chinese Room" by Michael West, July 13-23 in the Nikos Stage — has worked extensively on stage and film, including playing Steve Martin's wife in "Planes, Trains and Automobiles." On television, she's been seen in "Law & Order," the TNT series "Murder in the First," HBO's "The Sopranos" and Showtime's "Homeland."

Her Williamstown credits include "Summer and Smoke" (1986), "Ivanov" (1983), "Peer Gynt" (1984) and "Undiscovered Country" (1985).

O'Byrne is replacing the previously announced Michael Stuhlbarg in "The Chinese Room." The Ireland-born actor is a 2004 Tony Award winner for Bryony Lavery's drama, "Frozen." His performance in John Patrick Shanley's "Doubt" won him a 2004-05 Drama Desk Award and he's been a Tony nominee for his work in "The Beauty Queen of Leenane" (1998) and "The Lonesome West" (1999), both by Martin McDonagh, and Tom Stoppard's "The Coast of Utopia" trilogy (2007). His Broadway credits also include Conor McPherson's "Shining City" and Shanley's "Outside Mullingar." On television, he's been seen in "Mildred Pierce," for which he received a 2011 Emmy Award nomination.

Complete WTF 2016 season ticket and schedule information is available online at wtfestival.org.