Mark Harmon NCIS Special Agent Leroy Jethro Gibbs Actor, Executive Producer Sean Murray NCIS Special Agent Timothy McGee Actor Emily Wickersham NCIS Special Agent Eleanor "Ellie" Bishop Actor Wilmer Valderrama NCIS Special Agent Nicholas "Nick" Torres Actor Maria Bello Special Agent Jacqueline "Jack" Sloane Actor Brian Dietzen Dr. Jimmy Palmer Actor Diona Reasonover Forensic Scientist Kasie Hines Actor Rocky Carroll NCIS Director Leon Vance Actor, Director David McCallum Dr. Donald "Ducky" Mallard Actor Margo Harshman Delilah Fielding Guest Star Juliette Angelo Emily Fornell Guest Star Robert Mailhouse Dr. Malcolm Lucas Guest Star Jennifer Baxter Sienna Michaels a.k.a. Beach Bum Guest Star Chris Butler Clarence Guest Star Chet Grissom Rupert Kittridge Guest Star Gabriel Sousa Jared Guest Star Georgia Leva Lisa Guest Star Gwen Holloway A.A. Chairperson Guest Star Jessica Jade Andres Rachel Guest Star Isaac Gonzalez Rossi Marco Guest Star Joe Spano Tobias "T.C." Fornell Guest Star Vasthy Mompoint Janique 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 Donald P. Bellisario Executive Producer Marco Schnabel Writer