With changing combat environments, traditional measures of merit for fighter aircraft performance have largely proved insufficient to analyze combat capability. Combat experience has shown that the upper hand lies with an aircraft that has superior maneuverability across a large part of the flight regime. Agility metrics have come to provide a tool that would be capable of evaluating aircraft maneuverability over a wide range of conditions representative of combat, as well as provide aircraft designers the ability to design for superior maneuverability. Agility metrics have been shown to be sensitive to control laws and strategies, and aeroelastic phenomena, which means that they do not provide a parochial view of aircraft performance. In this review, agility metrics have been suitably classified, and some illustrative cases have been studied. The effects of advanced controls, such as thrust vectoring, and optimal maneuvers on combat performance, as suggested by agility metrics, have been investigated. The use of agility metrics for design has been discussed with examples of some well-known fighter aircraft.