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 David McCallum Dr. Donald "Ducky" Mallard Actor Gary Cole FBI Special Agent Alden Parker Actor Vanessa Lachey NCIS Special Agent Jane Tennant Guest Star Joe Spano Tobias "T.C." Fornell Guest Star Laura San Giacomo Grace Confalone Guest Star Novi Brown Olive Miller Guest Star Tess Aubert Piper Guest Star Jack McGee Richard "Rick" Jordan Guest Star Brandon Black Martin Polk Guest Star Joi Liaye Nina Miller Guest Star Jason Rogel Leo Guest Star David Bianchi Kyle Jennings Guest Star Oscar Gary Jr. Retired Navy Lieutenant Commander Thomas Miller Guest Star Taylor Bracken Navy Petty Officer Third Class Sally Jordan 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 Margaret Rose Lester Writer Michael Zinberg Director