| Dulé Hill as | Charlie (Charles) Young | Personal Aide to the President |
| Allison Janney as | C.J. (Claudia Jean) Cregg | Press Secretary |
| Joshua Malina as | Will (William) Bailey | Deputy Communications Director |
| Janel Moloney as | Donna (Donnatella) Moss | Assistant to Deputy Chief of Staff |
| Richard Schiff as | Toby (Tobias Zachary) Ziegler | Communications Director |
| John Spencer as | Leo Thomas McGarry | Chief of Staff |
| Bradley Whitford as | Josh (Joshua) Lyman | Deputy Chief of Staff |
| and Martin Sheen as |
Jed (Josiah Edward) Bartlet | President of the United States |
| Special Guest Stars | ||
| Mary-Louise Parker as | Amy (Amelia) Gardner | FLOTUS' Chief of Staff |
| Jesse Bradford as | Ryan Pierce | Intern |
| Gary Cole as | Robert "Bingo Bob" Russell | Vice President |
| Guest Starring | ||
| Ron Canada as | Theodore "Ted" Barrow | Under Secretary of State |
| Christopher Cousins as | Congressman Thiele | Rep. from Rhode Island |
| Tony Lee as | Jai Yung Ahn | Pianist |
| NiCole Robinson as | Margaret | Hooper (last name) / Assistant to Chief of Staff |
| Benjamin Brown as | Mike Wayne | Associate Counsel |
| Co-Starring | ||
| Kim Webster as | Ginger | Assistant to Communications' Director |
| William Duffy as | Larry | Congressional Liaison |
| Peter James Smith as | Ed | Congressional Liaison |
| Kris Murphy as | Katie | Witt (last name) / Reporter |
| Randolph Brooks as | Lyle | Arthur Leeds / Reporter |
| Nathan LeGrand as | Commerce Secretary | said "R" word in Economics meeting |
| Ron Marasco as | OMB Director | Economics meeting |
| Byron Chung as | N. Korean Handler | |
| Tom Yi as | Translator | |
| Sean Smith as | Immigration | in Mural Room |
| Ben Siegler as | George | Reporter |
| Mary Linda Phillips as | Aunt Barbara | from Wiconsin |
| Gil Glasgow as | Uncle Ted | from Wiconsin |
Adding to the realism, the new vice president, played by Gary Cole, will be in place by episode four or five, and around more than predecessor Tim Matheson."He needs to be brought up to speed," Wells says of the character. "He's also very ambitious."
"'West Wing's' fifth season: Politics NOT as usual "
by Jill Vejnoska
September 24, 2003
Atlanta Journal-Constitution
And, like Sorkin, who called his show "a valentine to public service," Wells believes the show's foundation is still good government, "without being Pollyannaish about the sausage making that is politics."
"Big changes await occupants of the "West Wing" White House"
by Gail Pennington
October 17, 2004
St. Louis Post-Dispatch
She [Paula Yoo] last wrote episodes for 2002-2003 season, leaving after creator Aaron Sorkin's departure. Her last script was "Han" about a defecting North Korean pianist, with inspiration from Yoo's five years in Korea and time as an accomplished violinist.
"'Sixteen' for Sammy and Yoo"
by Samson Wong
May 27, 2005
Asian Week