candidate: The main cast includes Mark Harmon as team leader Leroy Jethro Gibbs , Michael Weatherly as Senior Agent Anthony " Tony " DiNozzo , Cote de Pablo as Mossad Liaison Officer turned NCIS Agent Ziva David , Pauley Perrette as Forensic Specialist Abby Sciuto , Sean Murray as Special Agent Timothy McGee , David McCallum as Autopsy Technician Donald " Ducky " Mallard , Rocky Carroll as NCIS Director Leon Vance , and Brian Dietzen as Medical Assistant Jimmy Palmer .