The Opel Ascona was a medium-sized car produced by Opel, the German subsidiary of General Motors.

In the fall of 1970 Adam Opel AG presented its completely new vehicle range in Rüsselsheim (internal project code 1.450). The Opel Manta coupé was launched on September 9, followed by the Opel Ascona on October 28 in two- and four-door sedan forms, plus a three-door station wagon (called Caravan). These models were positioned between the existing Opel Kadett and the Opel Rekord.

The Opel Ascona was developed to give Ford a hard time (Ford was doing well selling the Taunus). The Opel Ascona A stayed in production until 1975. At that time, almost 692,000 verhicles of the first series were produced.

A small number were exported as the 'Opel 1900' to the United States, sold through Buick dealerships. They were eventually replaced by versions of the smaller Opel Kadett.

The 1975 Opel Ascona B was available as a two- or four-door sedan. There were related two- and three-door coupé models in the Opel Manta range.

In Britain, the Vauxhall Cavalier badge was used on both saloon and coupé models, which came out of the same factory in Belgium—the first Vauxhall to be built abroad. The front ends were different, featuring Vauxhall's trademark "droop snoot", as designed by Wayne Cherry.

A version of the Ascona B, featuring the front end of the Manta B, was sold in South Africa as the Chevrolet Chevair. This was in addition to a Chevrolet Ascona, identical in most respects to the Opel.

A 2·1 litre diesel model was added to the Ascona B range in 1978.

The Ascona C, part of General Motors' J-car project, was launched in 1981 and switched to front-wheel drive. The range added an option of a five-door hatchback bodystyle. The cars were also available in the UK as the Vauxhall Cavalier. The old Cavalier Coupé was phased out, though the Opel Manta was retained in the UK—the last car to be badged as an Opel in the UK before it was deleted in 1987. There were no longer sheetmetal differences between the Opel and Vauxhall models after 1981.

There was no station wagon version of the Ascona C; only Vauxhall in the UK brought in the rear ends of the Holden Camira Wagon and adapted them to the Cavalier. Nor was there a coup&eacute, although a version sold in Brazil, known as the Chevrolet Monza, included a locally designed three-door coupé.

Opel continued to use the Ascona nameplate until the Vectra was launched in 1988, although the Cavalier name was retained by Vauxhall until 1995.