This article refers to a class of aircraft. Light infantry is sometimes referred to in this fashion in the U.S. See: 7th Infantry Division (United States).

A light fighter or lightweight fighter is a type of fighter aircraft with a diminutive airframe, deliberately designed to fill a performance niche based on a high thrust-to-weight ratio and high maneuverability. The development of this concept was based on results from real world experience studies. In the U.S. ideas were founded upon shortcomings endured during the Vietnam War, while in Sweden the requirement was a Mach 2 capable versatile platform with good short-field performance for a defensive, dispersed basing plan in the event of an invasion. Typically, light fighters have been dismissed by military planners as being too limited in capability, but several light fighter designs already have proven combat records. Some of the light fighters of today are now being developed as or have variants converted into unmanned combat aerial vehicles to be added as force multipliers and minimize human casualties.

The Lightweight Fighter (LWF) program was a United States Air Force technology evaluation program initiated in the 1960s by a group of officers and defense analysts known as the "Fighter Mafia". It was spurred by then-Major  John Boyd's  Energy-Maneuverability (E-M) theory of maneuverability, which indicated that excessive weight would have severely debilitating consequences on the maneuverability of an aircraft. Boyd's design called for a light-weight fighter with a high thrust-to-weight ratio, a gross weight of less than 20,000 pounds (9,100 kg; half that of its counterpart, the F-15 Eagle), and high maneuverability. It resulted in the development of the  General Dynamics YF-16 and Northrop YF-17. Late in the program, in 1974, with the promise of European sales, the Air Force changed the program name to Air Combat Fighter (ACF), and committed to purchasing 650 models of the YF-16, adopted as the  F-16 Fighting Falcon. The U.S. Navy adopted a modified version of the YF-17 as the F/A-18 Hornet.