Fixed-wing aircraft is a term used to refer to what are more commonly known as aeroplanes in Commonwealth English (excluding Canada) or airplanes in North American English.

Fixed-wing aircraft include monoplanes, biplanes and triplanes; in fact all conventional aircraft that are neither balloons, airships, autogyros, helicopters or tiltrotors are fixed-wing aircraft.

The term embraces a minority of aircraft that have folding wings, intended to fold when on the ground, perhaps to ease stowage or facilitate transport on, for example, a vehicle trailer or the powered lift connecting the hangar deck of an aircraft carrier to its flight deck. It also embraces an even smaller number of aircraft, such as the General Dynamics F-111 Aardvark, Grumman F-14 Tomcat and the Panavia Tornado, which can vary the sweep angle of their wings during flight. In the early days of their development, these were termed "variable geometry" aircraft. When the wings of these aircraft are fully swept, usually for high speed cruise, the trailing edges of their wings abut the leading edges of their tailplanes, giving an impression of a single delta wing if viewed from above or below. There are also rare examples of aircraft which can vary the angle of incidence of their wings in flight, such the F-8 Crusader, which are also considered to be "fixed-wing".

Sir George Cayley, the inventor of the science of aerodynamics, was building and flying models of fixed wing aircraft as early as 1803, and he built a successful passenger-carrying glider in 1853, but it is known the first practical self-powered aeroplanes were designed and constructed by the Wright brothers. (Indeed, the German Karl Jatho had already constructed such 4 months earlier and made his first flight August 28, 1903 in Hanover.) Their first successful test flights were in December 17, 1903 and by 1904 the Flyer III was capable of fully-controllable stable flight for substantial periods. Strictly, its wings were not completely fixed, as it depended for stability on a flexing mechanism named wing warping. This was soon superseded by the competitive development of ailerons, attached to an otherwise rigid wing.