The Austin-Healey 100 is a sports car that was by Austin-Healey built from 1953 until 1956. The "100" was named by Healey for the car's ability to reach 100 mph (160 km/h); its successor, the better known Austin-Healey 3000, was named for the 3000 cc displacement of its engine.

The first 100s (series "BN1") were equipped with the same undersquare 87.3 mm (3.4 in) bore and 111.1 mm (4.4 in) stroke 90 bhp (67 kW) 2660 cc I4 engines and manual transmission as the stock A90, but the transmission was modified to be a three-speed unit with overdrive on second and top. A total of 10030 BN1s were built from May 1953 until replaced by the BN2 model in August 1955.

Built primarily with racing in mind, the aluminium-bodied "100S" (for Sebring) model developed 132 bhp (98 kW) at 4700 rpm. Only 50 production cars were made, plus an additional five works development/special test cars hand built by the Donald Healey Motor Company at Warwick. To minimize weight the cast iron cylinder head was replaced by an aluminium one, and the overdrive unit was not installed. Brakes were discs all-round, the world's first production car to feature them both front and rear. To further lighten the vehicle, bumpers and hood (convertible top) were eliminated, the grille reduced in size, and the windscreen made of plastic. In all, weight was reduced by approximately 200 lb (91 kg). The majority of 100Ss were two-toned white with Lobelia Blue sides. A handful were produced in solid Spruce Green and red, and single one in black.