Leslie Bibb - is set to join the cast of NBC's top medical drama "ER" next season. She will play Erin Harkins -- a medical student who comes to work in the ER. Bibb's deal is for five episodes with an option for more, and she will first appear in the second episode of the new season.
Bibb is best known for her lead role as blonde beauty Brooke McQueen on the WB Network's "Popular."
This past development season, she played the lead in Rod Lurie's two-hour drama pilot for ABC and DreamWorks TV, "Capital City." On the big screen, Bibb recently starred in "See Spot Run" and "The Skulls."
 

Don Cheadle - has signed on to do a multiepisode arc on NBC's medical drama "ER," playing a medical student who comes to the emergency room at Chicago's County General Hospital for his surgical internship.
He has signed on for a four-episode guest starring arc on the drama. The episodes will likely air during the November sweeps.
Cheadle's long list of feature credits include "Ocean's Eleven," "Boogie Nights," "Out of Sight," "Swordfish" and "Bulworth." He's also no stranger to television, having been a regular on both "Picket Fences" and "Golden Girls" spinoff "The Golden Palace."
Cheadle, 37, is also a current Emmy nominee for his role in the Showtime TV movie "Things Behind the Sun."
 

Tom Everett Scott - has signed on to do at least five, and possibly as many as eight, episodes of NBC's hit medical drama "ER,".
He will play Eric Wyczenski, an Air Force air traffic controller who comes to Chicago to visit his sister, nurse Abby Lockhart   (Maura Tierney).
Scott will first appear in the third episode of "ER's" ninth season this fall.
Scott's TV credits also include Darren Star's short-lived Wall Street drama "The $treet," the hit comedy "Grace Under Fire" and the telefilm "Inherit the Wind." On the features side, Scott has starred in such movies as the Tom Hanks-directed "That Thing You Do!" "An American Werewolf in Paris," "Dead Man on Campus" and "Boiler Room."

Sally Field - Two-time Oscar winner Sally Field reprises her Emmy Award-winning role on NBC’s “ER” this fall in the first of multiple episodes in which she portrays the mentally ill and problematic mother of Nurse Abby (Maura Tierney).Field will resume filming in September in the role she first originated on the popular drama series during the 2000-01 season over an arc of high-profile episodes. Her character -- who suffers from a bi-polar disorder -- will be reunited with her distrustful daughter as well as her son (recurring guest star Thomas Everett Scott, an Air Force veteran who is visiting Abby.She will reappear on the series in an episode scheduled to air on the network Nov. 21.

 

Michael Gross - revealed on the Today show  that he will be returning to ER next season to reprise his role as Jack Carter.  This has been unconfirmed.