Mark Harmon NCIS Special Agent Leroy Jethro Gibbs Actor, Executive Producer Sean Murray NCIS Special Agent Timothy McGee Actor Wilmer Valderrama NCIS Special Agent Nicholas "Nick" Torres Actor Brian Dietzen Dr. Jimmy Palmer Actor Diona Reasonover Forensic Scientist Kasie Hines Actor Katrina Law NCIS Special Agent Jessica Knight Actor Rocky Carroll NCIS Director Leon Vance Actor Gary Cole FBI Special Agent Alden Parker Actor David McCallum Dr. Donald "Ducky" Mallard Actor Pam Dawber Marcie Warren Guest Star Joe Spano Tobias "T.C." Fornell Guest Star Jason Wiles Tom Samuels a.k.a. Paul Lemere Guest Star John Hensley Phil Hanover Guest Star Emily Berry Gladys Guest Star Jaxy Boyd Michelle Guest Star Nohely Quiroz Carla Guest Star Chas. Floyd Johnson Executive Producer Mark Horowitz Executive Producer Frank Cardea Executive Producer George Schenck Executive Producer Steven D. Binder Executive Producer Scott Williams Executive Producer, Writer Donald P. Bellisario Executive Producer Terrence O'Hara Director