The Audi S8 is a full-size luxury car of the Audi S models produced by the German automaker Audi AG, manufactured by Audi Sport GmbH at the Neckarsulm plant. The S8 is the mechanically-upgraded, high-performance version of the Audi A8, fitted standard with Audi's quattro all-wheel drive system, and was only offered with a short-wheelbase for the first three generations, being joined by a long-wheelbase variant option for the fourth generation.

Audi S and RS models are a range of high performance versions of certain car models of the German automotive company Audi AG. These cars primarily focus on enhanced "sport" performance. Production of Audi "S" cars began in 1990 with the S2 Coupé, whilst the first "RS" car appeared four years later with the Audi RS 2 Avant.