Alfa Romeo Automobiles S.p.A. (Italian: [ˈalfa roˈmɛːo]) is an Italian luxury car manufacturer and a subsidiary of Stellantis. It was founded on 24 June 1910 in Milan, Italy, as A.L.F.A., an acronym for Anonima Lombarda Fabbrica Automobili. The brand is known for sport-oriented vehicles and has been involved in car racing since 1911. Alfa Romeo was owned by Fiat Chrysler Automobiles, which took over vehicle production until its operations were fully merged with those of the PSA Group to form Stellantis on 16 January 2021.

Alfa Romeo began with the purchase of the main factory building of French carmaker Darracq in Milan, which was closing up and selling all its assets. Its first car was the 1910 24 HP, designed by Giuseppe Merosi. Alfa ventured into motor racing, with drivers Franchini and Ronzoni competing in the 1911 Targa Florio with two 24-hp models. In August 1915, the company came under the direction of Neapolitan entrepreneur Nicola Romeo, who converted the factory to produce military hardware for the Italian and Allied war efforts. In 1920, the name of the company was changed to Alfa Romeo with the Torpedo 20–30 HP the first car to be so badged.

In 1921, the Banca Italiana di Sconto, which backed the Ing. Nicola Romeo & Co went bankrupt, and the government needed to support the industrial companies involved, of which Alfa Romeo was among, through the "Consorzio per Sovvenzioni sui Valori Industriali". In 1925, the railway activities were separated from the Romeo company, and in 1928 Nicola Romeo left. In 1933, the state ownership was reorganized under the banner of the Italian state industrial organization Istituto per la Ricostruzione Industriale (IRI), which then had effective control. The company struggled to return to profitability after World War II and turned to mass-producing small vehicles rather than hand-building luxury models. In 1954, it developed the Alfa Romeo Twin Cam engine, which would remain in production until 1994. The Istituto per la Ricostruzione (IRI), the state conglomerate that controls Finmeccanica sold the marque to the Fiat Group in 1986 due to the marque being unprofitable.

Alfa Romeo has competed successfully in Grand Prix motor racing, Formula One, sportscar racing, touring car racing, and rallies. It has competed both as a constructor and an engine supplier, via works entries (usually under the name Alfa Corse or Autodelta), and private entries. The first racing car was made in 1913, three years after the foundation of the company, and Alfa Romeo won the inaugural world championship for Grand Prix cars in 1925. The race victories gave a sporty image to the marque, and Enzo Ferrari founded the Scuderia Ferrari racing team in 1929 as an Alfa Romeo racing team, before becoming independent in 1939. Ferrari has had the most wins of any marque in the world.