candidate: The main cast during the filming of the third season included Mark Harmon as team leader Leroy Jethro Gibbs , Michael Weatherly as Senior Agent Anthony " Tony " DiNozzo , Cote de Pablo as Mossad Liaison Officer Ziva David , Pauley Perrette as Forensic Specialist Abby Sciuto , Sean Murray as Special Agent Timothy McGee , David McCallum as NCIS Medical Examiner Donald " Ducky " Mallard , and Lauren Holly as NCIS Director Jenny Shepard .