David James Elliott Lt., Lt. Cmdr. Harmon "Harm" Rabb, Jr. Actor Catherine Bell Maj., Lt. Col. Sarah "Mac" MacKenzie Actor Patrick Laborteaux Lt. j.g., Lt. Bud Roberts Actor Karri Turner Ensign, Lt. j.g. Harriet Sims Actor Scott Lawrence Cmdr. Sturgis Turner Actor Zoe McLellan Petty Officer Jennifer Coates Actor Chris Beetem Lt. Gregory Vukovic Actor David Andrews Maj. Gen. Gordon "Biff" Cresswell Actor Tammy Townsend Guest Star Zachary Bostrom Guest Star Michael Bellisario Guest Star Judith Hoag Guest Star Johanna Black Guest Star Harold Rossing Guest Star John Barton Guest Star Donald P. Bellisario Executive Producer Charles Floyd Johnson Executive Producer Stephen Zito Executive Producer, Writer Mark Horowitz Executive Producer Bradford May Director