The Opel Omega is an executive car marketed by the German automaker Opel between 1986 and 2003 in two generations, both manufactured at Opel's Rüsselsheim, Germany plant. The first generation, the Omega A (1986–1993), superseded the Opel Rekord, was voted European Car of the Year for 1987, and was available as a saloon or estate. The second generation, the Omega B, was manufactured from 1993-2003.

Rebadged variants of the Omega were marketed worldwide, including in North America as the Cadillac Catera, in Great Britain as the Vauxhall Carlton and South America as the Chevrolet Omega. Re-engineered versions were manufactured in Australia since 1997 and marketed as the Holden Commodore or Holden Calais, which were also exported to South America as the Chevrolet Omega from 1998.

Production of the Omega ended in 2003 without a direct replacement, except for the Australian re-engineered version that carried on until 2006.

The original Omega went into production in September 1986, as a replacement for the Opel Rekord, which had been in production since 1978. Sales began in November. The body was designed as an evolution of the previous Opel design theme engineered more towards aerodynamics in view of higher fuel prices and the general drive towards more fuel efficiency. The result was a remarkable drag coefficient of 0.28 (0.32 for the Caravan). The whole development program cost 2 Billion Deutschmark.