Information derived from the imdb. e=episodes. Specific titles noted only for 2015-on. All actors in 2+ episodes and/or playing comic book characters noted. Actors in only 1 episode gradually being folded in.
Timothy Bottoms (George W. Bush): in Men's Group (2016), How Not to Propose (2015); Tar (2018) in post-production; as Self: Q N' A with Mikki and Shay (1e 2015), The 19th Annual Satellite Awards (2015).
Carrie Quinn Dolin (Laura Bush): last known acting role in 2003.
Kurt Fuller (Karl Rove): in Law & Order: Special Victims Unit (2018), His Wives and Daughters (unknown e 2017), Huntsville (2017), Psych: The Movie (2017), American Dad! (1e 2017), Bull (2017), Kings of Con (6e 2016-2017), Rosewood (3e 2015-2017), The Philosophy of Phil (2017), The Wolves of Savin Hill (2017), Small Victories (2016), An American Girl Story - Maryellen 1955: Extraordinary Christmas (2016), BrainDead (1e 2016), The Good Wife (3e 2015-2016), Highston (2015), A Light Beneath Their Feet (2015), Bones (1e 2015), Film Pigs (1e 2015), Hot in Cleveland (1e 2015), Accidental Love (2015); Deported (2017), Baja (2018) completed; Office Uprising (2018) in post-production; The Potters (nd) in pre-production; The Truth About Harry Quebert Affair (2018) announced; as Self: WWE Monday Night RAW (1e 2017), Cleanin' Up the Town: Remembering Ghostbusters (2017), Kings of Conversation (1e 2016), Ghostheads (2016).
Marcia Wallace (Maggie Hawley): died in 2013.
Kristen Miller (Princess Stevenson): in Eliza Sherman's Revenge (2017), Meet My Valentine (2015).
John D'Aquino (Larry O'Shea): in K.C. Undercover (1e 2018), Disjointed (1e 2018), In Sanity, Florida (4e 2017), The 60 Yard Line (2017), NCIS: Naval Criminal Investigative Service (1e 2015), The Mentalist (1e 2015); as Executive/Producer: Cattle Call (2017), Reasons to Live (2017; also Writer/Director), Oui Oui: Wee Wee (2017), Tabula Rasa (2017), Humans in Training (2016), Nowhere Cafe (2016; also Writer), Astronaut Camp (2016), Penguin Flu (2016), Boundless (2015), Cartwheels and Backflips (2015; also Writer/Director), Pow Wham Night Wild (2015).
Toddy Walters (Tour Guide): only known subsequent acting role in 2010 but Stadium Anthems (2017; also Musician/Composer/Associate Producer) completed; as Vocals in 2010.
Chris Borkovec (Officer Smiley): last known acting role in 2011.
Bob Legionaire (Charlton Heston): last known acting role in 2003.
Robert Machray (Moose): last known acting role in 2011.
Valerie Mahaffey (Janet Rove): in Young Sheldon (5e 2017-2018), The Man in the High Castle (3e 2016), No Pay, Nudity (2016), Sully (2016), The Mindy Project (1e 2016), Impastor (1e 2015), Devious Maids (2e 2015), Workaholics (1e 2015); The Witch Files (nd) in post-production.
David Norona (Ramon): in The Gifted (3e 2017-2018), Designated Survivor (1e 2016); I Can Only Imagine (2018) completed; as Writer/Director, post-production: The Bright Ones (2018).
Joseph Ruskin (Dr. Jack Kevorkian): died in 2013.
Edmund L. Shaff (Dick Cheney): in Modern Family (1e 2015).
Guy Siner (Dr. Thomas Klestil): last known acting role in 2014; as Self: AIR Theatre (2017).
Lisa K. Wyatt (Joyce): in The Angeleno Hunter (2017), Superstore (1e 2016), Internet Famous (2016), D8ting (2015), Tenured (2015); American Woman (1e 2018), Heavenly Deposit (2018) in post-production; UnCorked (10e 2018; also Executive Producer; 2e as Writer, 1e as Director) filming; Magnum Farce (nd) announced; as Writer/Director: Maiden Voyage (2016), Fire's Out (2016), The Holiday Hostess (2015).
Akima (Kanook-Nook): died in 2014.
Christopher Birt (Leron): last known acting role in 2012.
Juanita Jenning (Ms. Clea): in Star (6e 2017), Detroiters (1e 2017), Major Crimes (1e 2015).
Madison Mason (Donald Rumsfeld): in NCIS: Los Angeles (1e 2017), Girl Meets World (1e 2015).
Ivan Naranjo (Punanee Chief): died in 2013.
Marte Boyle Slout (Barbara Bush): no known subsequent acting roles.
George Brandon (Felix's Assistant): no known subsequent acting roles.
Vanessa Hendrix (Karl's Daughter): last known acting role in 2005.