The fifteenth and final season of the American fictional drama television series ER premiered on September 25, 2008 and concluded on April 2, 2009, in a two-hour episode preceded by a one-hour retrospective special. The season consists of 22 episodes.
The final season opens up revealing Gregory Pratt is the victim of the ambulance explosion. Despite the rallying efforts of his workplace colleagues, he succumbs to his injuries and dies. The season introduces Cate Banfield as new ER chief, a woman with a seemingly mysterious past with County General. Abby and Kovac leave for a new life in Boston, Brenner must deal with issues surrounding his childhood, Sam and Gates' relationship suffers a setback while Neela is forced to make some tough decisions, both personal and professional.
To mark the end of the series and draw closure, several former cast members make a return to the show. Greene and Romano appear in a flashback episode that explores Banfield's history with County General while Carter returns to work at County although, unbeknownst to his colleagues, he is in desperate need of a kidney transplant while the likes of Benton, Ross, Lewis, Hathaway, Corday, Weaver and Barnett all make surprise returns.
Main cast
Maura Tierney as Dr. Abby Lockhart, Chief Resident
Mekhi Phifer as Dr. Greg Pratt, Attending Physician
Parminder Nagra as Dr. Neela Rasgotra, Third Year Surgical Resident
John Stamos as Dr. Tony Gates, Third Year Resident
Linda Cardellini as Nurse Samantha Taggart
Scott Grimes as Dr. Archie Morris, Attending Physician
David Lyons as Dr. Simon Brenner, Attending Physician
Angela Bassett as Dr. Catherine Banfield, Chief of Emergency Medicine
The final season included special appearances by departed regular and recurring cast members:
Anthony Edwards as Dr. Mark Greene (episode 7)
George Clooney as Dr. Doug Ross (episode 19)
Julianna Margulies as Nurse Carol Hathaway (episode 19)
Laura Innes as Dr. Kerry Weaver (episodes: 7, 22)
Alex Kingston as Dr. Elizabeth Corday (episodes: 12, 22)
Eriq La Salle as Dr. Peter Benton (episodes: 19, 22)
Paul McCrane as Dr. Robert Romano (episode 7)
Sherry Stringfield as Dr. Susan Lewis (episode 22)
Shane West as Dr. Ray Barnett (episodes: 5, 20, 21)
Noah Wyle as Dr. John Carter (episodes: 16–19, 22)
Goran Visnjic as Dr. Luka Kovač (episode 3)
Returning recurring characters
Abraham Benrubi as Jerry Markovic (multiple episodes)
Ellen Crawford as Nurse Lydia Wright (finale)
Hallee Hirsh as Rachel Greene (finale)
William H. Macy as Dr. David Morgenstern (episode 14)
Thandie Newton as Makemba "Kem" Likasu (finale)
Matthew Watkins as Reese Benton (finale)
Tom Arnold (episode 21)
Ernest Borgnine (finale)
Louis Gossett Jr. (episode 15)
Rooney Mara (episodes 19 & 21)
Susan Sarandon (episode 19)
Carl Weathers (episode 6)
Christopher Chulack – Executive producer
Michael Crichton – Creator/Executive producer
John Wells – Executive producer
David Zabel – Executive producer
Joe Sachs – Executive producer
Janine Sherman Barrois – Executive producer
Lisa Zwerling – Co-executive producer
Tommy Burns – Producer
Wendy Spence Rosato – Producer
Charles M. Lagola – Production designer
Arthur Albert – Director of photography
Martin Davich – Music
Randy Jon Morgan, A.C.E. – Editor
Mimi Leder, a frequent director during ER's first two seasons, returned as a director for the episode "A Long, Strange Trip"
Rod Holcomb, the director of the 1994 pilot episode as well as several other early episodes, returned to direct two episodes in this season, among them the series finale
