The Opel Admiral was a luxury car made by the German car manufacturer Opel from 1937 to 1939 and again from 1964 to 1977.

The first Admiral was introduced in 1937 as an attempt to challenge large luxury cars from Horch, Mercedes-Benz and Maybach. It was available as a 4-door saloon or cabriolet. The car was equipped with a 3.6 litre straight 6 with a top speed of 132 km/h (82 mph). The production of the Admiral was cancelled in 1939 when the Opel factory started producing war material.

In 1964, Opel introduced its KAD (Kapitän, Admiral, Diplomat) models. The Admiral served as the middle model in this three-car range and was equipped with either a 2.6 litre straight-6 OHV of 100 PS (74 kW; 99 hp) providing a top speed of 158 km/h (98 mph), and, from September 1965, with a 2.8 liter-straight six CIH of 125 PS (92 kW; 123 hp), that made the car reach a top speed of 170 km/h (106 mph). The 2.6l straight-six was discontinued in 1965. Additionally, the Admiral could be equipped with the Chevrolet-sourced 4.6 l-V8 also used in the Opel Diplomat. In late 1967, a new two-barrel HL version of the 2.8 l six (140 PS (103 kW; 138 hp)) was introduced. At the same time, all KAD models received rub strips on their flanks, a reworked ZF recirculating ball steering and a collapsible steering column.