48 celebrities you may have forgotten were on 'The West Wing'

In the episode, "The Supremes," Close plays a potential Supreme Court justice, Lang, who is thought to be "too liberal" to actually secure the nomination.

The future "Friday Night Lights" star appeared in four episodes throughout season three: "Manchester Part I," "Manchester Part II," "Ways and Means," and "Gone Quiet" as a campaign staffer.

Dern's character spends most of the episode, which is aptly titled "The U.S. Poet Laureate," sparring with Toby Ziegler, the White House communications director, who is attempting to convince her to not speak out about the US' lack of support for an anti-landmine treaty.

Quincy is a Republican lawyer chosen in season four to replace the previous Republican White House counsel, Ainsley Hayes. He appeared in episodes "Evidence of Things Not Seen," "Life on Mars," and "Separation of Powers."

Just a few years later, Perry would team up with creator Aaron Sorkin again to star on "Studio 60 on the Sunset Strip" alongside "West Wing" alum Bradley Whitford.

Harmon was in four episodes in 2002 — "Enemies Foreign and Domestic," "The Black Vera Wang," "We Killed Yamamoto," and "Posse Comitatus" — just one year before he began starring on "NCIS" as Jethro Gibbs, a role he still plays today.

Hogan's main concern in her one episode, "The Black Vera Wang," was finding a dress for her junior prom.

In the premiere, "20 Hours in America Part I," Adams plays a farmer named Cathy who tries to help Toby, Josh Lyman (deputy chief of staff), and Donna Moss (Josh's assistant) return to the presidential motorcade, which mistakenly left without them.

A pre-"Modern Family" but post-"Married with Children" O'Neill appeared as Governor Baker, a potential Democratic presidential nominee, in "A Change Is Gonna Come," "In the Room," "Things Fall Apart," and "2162 Votes."

Lynch appeared in two high-stakes episodes — the season two premiere "In the Shadow of Two Gunmen Part I," and the season two finale "Two Cathedrals."

During the episode, "The Benign Prerogative," Meeshel spends time getting to know Charlie Young, the president's body man and close confidante, before he finds out she's a new reporter on the White House beat.

Walken temporarily becomes president due to the kidnapping of President Bartlet's daughter Zoey, and he chafes with the staff, as he's a Republican. He appears in "Twenty Five," "7A WF 83429," "The Dogs of War," and "The Stormy Present."

During the episode, "Duck and Cover," a nuclear power plant comes dangerously close to a meltdown, which turns the tide of the upcoming presidential election.

Huffman, who had starred on Sorkin's first TV show "Sports Night," appears in the episode "The Leadership Breakfast" as a Republican operative who plays on Toby's genuine desire for bipartisanship.

We'd like to think Offerman's "Parks and Rec" character, Ron Swanson, would get along with Jerry, who appears in the episode "The Crackpots and These Women" and advocates for a wolf-only highway so the animals can travel safely.

Slater appeared in three episodes ("Election Night," "Process Stories," and "Arctic Radar") as a Republican military officer who was willing to trade votes with Donna after she realized she accidentally voted for the Republican candidate, instead of her boss, President Bartlet.

Around five years before Edelstein starred on "House" as the no-nonsense Dr. Lisa Cuddy, she was in the pilot, "Post Hoc, Ergo Propter Hoc," "The State Dinner," "In Excelsis Deo," and "Lies, Damn Lies and Statistics."

The episode in question, "The Long Goodbye," focuses on CJ's return to her hometown for her 20th high school reunion, while also dealing with her father's Alzheimer's disease.

A far cry from Handler's "Sex and the City" character, the charming, if a bit schlubby, divorce lawyer Harry, Doug constantly clashed with Bartlet's staff in his season-three episodes ("Manchester Part I," "Manchester Part II," and "Ways and Means").

Isaacs appeared in the last two episodes of season five ("Gaza" and "Memorial Day") and the premiere of season six ("NSF Thurmont") as Donna's photojournalist love interest Colin, who is in the Gaza Strip with her when she's attacked.

In season one's "Take This Sabbath Day," Emmerich's character is a lawyer looking for a way to get the president to stop his client's upcoming execution.

Initially, Place's character appeared in season two's "Ellie," as both the godmother to one of President Bartlet's daughters (the titular Ellie) and the surgeon general who clearly states that there aren't any known serious side effects to smoking weed.

She reappears in two season-six episodes ("In the Room" and "Impact Winter") when the president has a serious MS attack during a trip to China.

You may recognize McRaney from his role in "One Tree Hill" as Nathan's overbearing grandpa Royal, or for his Emmy-winning role as Dr. K in "This Is Us."

But before that, he was in season three's "War Crimes," cautioning Leo against an international war crimes tribunal. He reappears in an episode in season five, "Memorial Day."

Brolin, husband to Barbra Streisand and father to Josh Brolin, appeared in season three in "Posse Comitatus" and in season four's "Game On" as President Bartlet's opposition and the governor of Florida.

Agent Davis was assigned to Zoey Bartlet, the youngest Bartlet daughter. He's introduced in the episode "Commencement," and he deals with her kidnapping in "Twenty Five."

In "Dead Irish Writers," Dalton is a former physics professor of Sam's who wants the government to invest in a particle accelerator.

Mendoza is introduced in the season-one episode "The Short List" as a potential nominee for the Supreme Court. He pops up later in the season, in "Celestial Navigation," after he's mistakenly pulled over while driving and later arrested for no reason.

Williams is in episodes "Undecideds" and "Election Day Part I."

Norris, who played Hank on "Breaking Bad," appeared in two episodes in season seven ("The Al Smith Dinner" and "The Cold") as Hodder, who tries to convince Republican candidate Senator Arnold Vinick to appeal more to the Republican base.

Gallagher Jr. appeared in both parts of season four's premiere, "20 Hours in America," as one of the residents of Indiana who Josh, Toby, and Donna come into contact with while stranded.

In 2012, 10 years later, he began playing senior news producer Jim Harper in "The Newsroom."

Fichtner, whom you might recognize from "Armageddon," "The Perfect Storm," or "Veep," to name a few, played a bright young conservative judge whom the main characters convince the president to nominate to the Supreme Court, so they can push through a liberal Chief Justice.

Ramsey appears in two episodes — "Welcome to Wherever You Are" and "Election Day Part I" — as Teddy.

Just a few years later, he'd begin starring on "Arrow" as John Diggle, a character that has outlived the show and pops up on multiple other series. This year alone, he was on "Batwoman," "DC's Legends of Tomorrow," "The Flash," "Superman and Lois," and "Supergirl."

In "Six Meetings Before Lunch," Lumbly plays the nominee for assistant attorney general for civil rights, who advocates for reparations for Black Americans.

The episode sees Pounder's character, best known for her roles in "NCIS: New Orleans," "The Shield," and "ER," called into the White House after she calls many Republicans racist on national TV.

Memorably, Tribbey makes his entrance holding a cricket bat and threatening to hit people with it in the season-two episode "And It's Surely to Their Credit" — only the "Night Court" star could make him likable. We wish he'd stuck around for more.

Officially, McShane's character from "Enemies Foreign and Domestic" is named Nikolai Ivanovich.

Something fun about "The West Wing" is that it's kind of unclear when the "real world" stops existing and when the show's universe takes over American history.

An example of that is Cromwell's President Newman, whom we meet in "The Stormy Present" at a funeral for another former president.

Just one year before he'd start playing Dr. Webber on "Grey's Anatomy" — a role he still holds today — Pickens Jr. appeared in the episode "Full Disclosure" as a DC mayor asking for the White House to endorse school vouchers.

Professor Lessig is brought in by Toby to help the country of Belarus draft a new constitution, though the two butt heads.

In just his second-ever TV performance, Burrell made an impression as Starks in season three's "The Women of Qumar."

Weil's scene, in which she tells off Sam for not really knowing anything about the programs he's attempting to cut in "Take Out the Trash Day," remains iconic over 20 years later.

He appeared in the episode "Bad Moon Rising."

Young would go on to play FLOTUS and eventual POTUS Mellie Grant in "Scandal," but first, she played a North Carolinian lawyer in "The Stormy Present."

Benson's full character name, according to IMDb, is "Girl."

He appeared in the episode "Two Weeks Out."

Intern Bruce, Burtka's second credit ever, only appeared in "The Black Vera Wang."

Gina appeared in five episodes as one of the agents assigned to Zoey's detail — she was in "20 Hours in LA," "The White House Pro-Am," "Six Meetings Before Lunch," "What Kind of Day Has It Been," and "In the Shadow of Two Gunmen Part I" — and critically noticed a shooter who was attempting to assassinate President Bartlet.

Reddick, who also played a police officer in "The Wire," appears in the first holiday episode of "The West Wing," called "In Excelsis Deo."

He plays a "mysterious foreign operative" whom Josh meets up with after a terrorist attack in Gaza.