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 Timothy Busfield Danny Concannon Guest Star Holmes Osborne Congressman Peter Lillienfield Guest Star Mason Adams Justice Joseph Crouch Guest Star Ken Howard Judge Peyton Cabot Harrison III Guest Star Edward James Olmos Judge Roberto Mendoza Guest Star Kathryn Joosten Mrs. Landingham Guest Star NiCole Robinson Margaret Guest Star Devika Parikh Bonnie Guest Star Kris Murphy Katie Witt Guest Star Peter James Smith Ed Guest Star Aaron Sorkin Executive Producer, Writer Thomas Schlamme Executive Producer John Wells Executive Producer Kristin Harms Producer Llewellyn Wells Producer Patrick Caddell Writer Bill D'Elia Director