Martin Sheen President Josiah "Jed" Bartlet Actor John Spencer Chief of Staff Leo McGarry Actor Rob Lowe Sam Seaborn Actor Bradley Whitford Dep. Chief of Staff Josh Lyman Actor Richard Schiff Communications Dir. Toby Ziegler Actor Allison Janney Press Secretary Claudia Jean "C.J." Cregg Actor Moira Kelly Mandy Hampton Actor Dulé Hill Charlie Young Actor Janel Moloney Donna Moss Actor Michael McGuire Congressman Cal Tillinghouse Guest Star Thom Barry Congressman Mark Richardson Guest Star Jay Underwood Congressman Christopher Wick Guest Star Mark Blum Rep. Katzenmoyer Guest Star Sara Botsford Jenny McGarry Guest Star Jillian Armenante Leela Guest Star Kathryn Joosten Mrs. Landingham Guest Star Tim Matheson Vice President John Hoynes Guest Star NiCole Robinson Margaret Guest Star Devika Parikh Bonnie Guest Star Aaron Sorkin Executive Producer, Writer Thomas Schlamme Executive Producer John Wells Executive Producer Kristin Harms Producer Llewellyn Wells Producer Michael Lehmann Director