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, Director Gary Cole FBI Special Agent Alden Parker Actor David McCallum Dr. Donald "Ducky" Mallard Actor Jason Wiles Paul Lemere Guest Star Gary Reichman Phil Hanover Guest Star Valarie Pettiford Sonia Eberhart Guest Star Anna Campbell Army First Lieutenant DFAS Andrea Falco Guest Star Allan McLeod Ted Guest Star Troy Vincent Lawyer Guest Star P.J. Johal Doctor Guest Star Karina Bonnefil Alexis Guest Star Sarah Khasrovi Patty Guest Star Kim Reed Nurse #1 Guest Star Kendra Munger Nurse #2 Guest Star Karina Noelle Castillo FBI Agent Ramirez Guest Star Ashley Dulaney Rebecca 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