F-4 Lightning, the photographic reconnaissance version of the P-38 Lightning fighter aircraft

F4U Corsair, a United States Navy fighter aircraft in World War II and the Korean War

Final four, mostly used in sporting events

Fantastic Four, The Marvel Superheros

F-number f/4, a standard expressing the diameter of the aperture on a camera

F4F Wildcat, a United States Navy fighter aircraft in World War II

4F - the Selective Service System

function key, on a computer keyboard

The MV Agusta F4 series of motorcycles

Factory Records fourth incarnation, run by Tony Wilson

F4, a tornado intensity rating on the Fujita scale, suggesting a violent tornado

F4D Skyray, a United States Navy fighter aircraft used in the 1960s

F4 (band), the former name of boy band JVKV from Taiwan

Bird's Opening in chess is characterised by 1. f4

USS F-4 (SS-23), a United States submarine which sunk near Honolulu harbor in 1915

Nikon F4 camera

F4 (mathematics), one of the five exceptional simple Lie groups

Albarka Air IATA airline designator

F4 layout, in automobiles, also known as front-engine, four-wheel drive

F4 (paper), paper format used frequently in the South East Asia region

Faugère F4 algorithm for the calculation of a Gröbner basis

F-4 Phantom II, a supersonic fighter-bomber made by McDonnell Douglas, or any one of the F-4 Phantom II variants

Form F-4, an SEC form used to register securities