The Bentley Arnage is a car produced by Bentley in the United Kingdom beginning in late 1998. Although having undergone various alterations, much of the design remained the same. This vast car is more than 5 m long, almost 2 m wide, and having a mass of over 2.5 metric tonnes.

The Arnage was originally launched with a 4398 cm³ BMW V8 engine, with twin turbochargers, developing some 350 bhp (260 kW). It followed the launch of its shorter-lived twin, the Rolls-Royce Silver Seraph. The basic Arnage was renamed the Arnage Green Label in 2000, its last model year.

It was joined in 1999 by the Arnage Red Label, which boasted torque of 835 N·m—the greatest amount for a four-door car at the time. The Red Label saw the return of the Rolls-Royce 6.75 L V8 engine, but mated to a Garrett AiResearch turbocharger. Customers associated the traditional engine with Bentleys, rather than the smaller BMW unit. Engineering for the insertion of this unit was done at Crewe, after Volkswagen, which had become Bentley's parent company, had threatened to do it in Germany when Bentley's UK engineers initially claimed the task was impossible. At the time, there were reports that Volkswagen wanted Bentley to be independent of BMW engineering.

A long-wheelbase version of the Red Label was launched at the Detroit Motor Show in 2001. The Red Label models were replaced in 2002.

In 2001, the Arnage RL, a long-wheelbase model, was launched, featuring twin Garrett T3 turbochargers and the 6.75 L engine, developing 400 bhp (298 kW).

In 2002, Bentley announced its "Series Two" Arnages. These featured some detail improvements, with the Red Label giving way to the Arnage R. This model was launched to contrast the Arnage T, which was developed to be more sporting. The Arnage R features two Garrett T3 turbochargers, as with the RL. A torque of 616 lbf·ft (835 N·m) is delivered to the Arnage R and Arnage RL. The Arnage R does 0–60 mph (97 km/h) in 5.9 s; the Arnage RL takes 6.0 s. Top speed is a claimed 155 mph (250 km/h).

The Arnage T, also from 2002, was claimed to be the most powerful roadgoing Bentley at its launch at the Detroit Motor Show. As with the Arnage R, there were twin turbochargers, but tuned to develop 450 bhp (340 kW) and 645 lbf ft (875 N·m). The Arnage T's 0–60 mph time is 5.5 s; a top speed of 168 mph (270 km/h) is claimed.

This model was joined in late 2003 by a brand new Bentley coupé called the Continental GT, but on an unrelated platform.

The Arnage range was facelifted in 2004, with a front end resembling that of the Continental GT.