Commander Caitlin Pike JAGC, USN (played by Andrea Parker) is a character in the JAG TV series. Insignia of a United States Navy Commander Commander is a military rank used in many navies but not generally in armies or air forces. ... Judge Advocate Generals Corps, also known as JAG, is the judicial arm of the United States armed forces, consisting of autonomous departments in the Air Force, Army and Navy. ... The United States Navy (USN) is the branch of the United States armed forces responsible for naval operations. ... Andrea Nicole Parker (born March 8, 1969 in Monterey County, California) is an American actress and former ballet dancer. ... For other uses, see JAG (disambiguation). ...