The Opel Insignia is a large family car (D-segment in Europe) developed and produced by the German car manufacturer Opel from 2008 to 2022. Taking its name from a 2003 concept car, the model line serves as the flagship model, slotted above the Astra and Corsa in size. The Insignia serves as the successor to both the Signum and Vectra model lines, replacing both vehicles under a single nameplate. The model line was offered in four-door sedan/saloon body styles, five-door liftback, and as a five-door station wagon/estate.

Sold worldwide, the Insignia is marketed under multiple nameplates. Under Opel tradition, the model line is marketed by Vauxhall in the United Kingdom, taking on the Vauxhall Insignia name. Both generations of the model line have been marketed in North America and China as the Buick Regal (sales of the Regal continue in China). In South America, the vehicle was originally due to be marketed as the Chevrolet Vectra, but went on sale as the Opel Insignia instead. GM Australia marketed the second-generation Insignia as the Holden Commodore (ZB) until discontinuing both the model line and the Holden brand at the end of 2020.

The launch vehicle of the GM Epsilon II platform, Opel produces the Opel/Vauxhall Insignia in Adam Opel AG Werk Rüsselsheim in Rüsselsheim, Germany. SAIC-GM produces the Buick Regal in Shanghai, China (exclusively for the Chinese market).

In February 2022, Opel confirmed that the Insignia would be discontinued after the model completes its current generation lifecycle at the end of the year without a successor planned, due to poor sales and plans to shift Opel into selling the Astra, Corsa and SUVs like the new Frontera.

In December 2006, Vauxhall stated they would retire the Vectra nameplate from the previous model. Then General Motors Europe president, Carl-Peter Forster, explained that the all new car would be "a radical departure" from the current model and that the "Vectra" name would be dropped to reflect this change. In late 2007, Vauxhall confirmed that the successor's name would be Insignia.

With the Insignia, Opel planned to regain some of the market share that the executive Omega once occupied during its production.

The Insignia debuted as the Vauxhall Insignia at the 2008 British International Motor Show in London on 23 July. It then went on sale in European dealerships in October 2008 for the 2009 model year as a five-door liftback and five-door estate dubbed Sports Tourer – a departure for Opel which traditionally used the "Caravan" name to denote the estate bodystyle. It was the first production car to be based on the Epsilon II platform, which was also used on other models such as the 2010 Saab 9-5 and the Chevrolet Malibu.

Design wise, the Insignia offers 30 mm (1.2 in) more knee room than the Vectra. The saloon and liftback variants have the same 4.83 m (190.2 in) length, while the estate version is slightly longer at 4.91 m (193.3 in). All three models share the same, 2.73-metre (107.5 in) wheelbase.